typescript, infer, incomplete, unknown, generic Expected behavior: The compiler should be able to extract information of the generic Item type from the function definition and infer string . If you do not annotate a variable or did not initialize with a value, then typescript will infer it as type any. In this example, the TypeScript compiler tries to infer the return type of the add() function to the number type, which is expected.. If you continue to use this site we will assume that you are happy with it. Type inference in conditional types. In the process the compiler strips away all function and method bodies and preserves only the signatures of the types that are exported. Common cases include arguments to function calls, right hand sides of assignments, type assertions, members of object and array literals, and return statements. The compiler determines the type as union type of number & null. The strictBindCallApply compiler option enables stricter checking of the bind, call, and apply methods on functions. readonly properties (TypeScript 2) like in C# Flow does not feature those or any other syntactic sugar, as it is a checker only. Because of the syntax overhead of TypeScript-ReScript inter-operation, I recommend doing it as little as possible, using each language in separate areas of your app. For example, in … To correct this, instead explicitly provide the type when no one type is a super type of all other candidates: When no best common type is found, the resulting inference is the union array type, (Rhino | Elephant | Snake)[]. declare function selectFormat (format: FormatKeys): void In the example above, FormatKeys is never , because there are no common, intersecting keys within this type. A decorator factory is a function which returns the expression that will be called by the decorator at runtime. It's a TypeScript-first schema declaration library with rigorous inferred types, incredible developer experience, and a few killer features missing from the existing libraries. interface User {id: number; name: string; address: {street: string; city: string; country: string;};}. TypeScript decides which types are assignable to each other using an approach called 'structural typing'. Namely, we’ll discuss where and how types are inferred. TypeScript's type system has grown steadily more powerful over the past five years, allowing you to precisely type more and more patterns in JavaScript. Here we made on into a generic method. The TypeScript infers them as any, but a compiler error results if the above flag is set to true. For example, a code editor can incorporate the TypeScript language service and use the service to find the members of a string object as in the following screen shot. Let’s give this a try: Perfect! Basics # In TypeScript, there are several places where type inference is used to provide type information when there is no explicit type annotation. In TypeScript, when you declare a variable and assign a value to it in the same statement, TypeScript annotates the variable with the type it receives from the value. Records There is only one type which does need a type declaration, which is the record type. You do lose the return type inference, though. In such a circumstance, the Typescript makes an attempt to infer the type of the variable. return_type of the function is optional. The definitions in declaration files are only used by the compiler at compile-time, and is not included in the resulting code. For example: In this example, best common type has a set of four candidates: Animal, Rhino, Elephant, and Snake. If you're using Flow, this article will still make sense, but TypeScript and That let has been converted to var. If no implicit type specified or value assigned, then typescripts infers it as any. For example. We didn’t give the compiler any tips on how we will use it. CalcSum.d.ts Typescript makes an attempt to deduce the type from its usage. TypeScript can also infer generic types by its usage. In these modules we try to get as good autocompletions as possible and help our developers write better code, with generics to infer types. If you’re not familiar with TypeScript, it’s a language that adds optional static types to JavaScript. Here is another example of a mixed type of string & number. A more explicit version would have a lot more number. The TypeScript interpreter is smart enough to infer the generic parameter from this argument. Types by Inference. The Type inference for the complex data types like objects works in similar ways. Here we are given two choices for the type of the array: number and null. In this article, I used TypeScript v3. Zod is a validation library designed for optimal developer experience. The TypeScript compiler is smart enough to deduce (infer) the type by looking at the type and shape of the value we are assigning to the variable in the declaration. Here we made on into a generic method. But there are circumstances where inferring type as any may result in unexpected errors. typescript-infer-types. The other data types result in compiler error. While in our declaration file we can declare a Component type, the component is still written in plain Javascript. In the following sections, we’ll explore some of the nuances in how types are inferred. One is explicit and the other one is implicit Explicit Typing is when we just declare the variable with the types. We call this Type Inference. Hello, this is starting the article for advanced TypeScript tutorial series. Learn how your comment data is processed. When a type inference is made from several expressions, the types of those expressions are used to calculate a “best common type”. TypeScript will infer from the following function definition that the function f has return type string. Similarly, the data type of the array is based on its initial element assigned to it. This means you don't need any additional tooling to use TypeScript with Vue - it has first-class citizen support. Since I don’t want to maintain extra types (that might be error-prone), I need to somehow transform the union of my video formats to an intersection of video formats. In the above code. Learn TypeScript: Types Cheatsheet | Codecademy ... Cheatsheet This is known as “contextual typing”. TypeScript uses static typing, meaning that you can give a type to a variable during declaration. TypeScript can figure out that it is a string, and therefore we now have a adequately typed variable. Such inferred type variables may be referenced in the true branch of the conditional type. This tutorial provides a brief overview of TypeScript, focusing on its type system. TypeScript 2.8 is here and brings a few features that we think you’ll love unconditionally! // ^ = let zoo: (Rhino | Elephant | Snake)[]. As we expect, TypeScript doesn’t infer this type as we would want: So, what can we do? We looked at in the previous example. TypeScript doesn’t have many built-in data types you can use to declare variables—just string, number and Boolean. In my projects, I have many generic functions that compose each other and TS' inference isn't always accurate. For example: let counter: number; However, if you initialize the counter variable to a number, TypeScript will infer the type the counter to be number. TypeScript infers that result is a number despite not adding a return type to divide, or a type declaration to the result variable. Understanding this concept will give you an advantage when working with existing JavaScript. If you don't know what Type Inference is, refer to the official guide. Type inference with generics for objects. The TypeScript compiler uses declaration files to infer types and check validity of your code for the described library. Let's browse to the TypeScript playground and enter the following variable declaration into the left-hand pane: let unitPrice: number; The transpiled JavaScript will appear on the right-hand side as follows: var unitPrice; Note. And it's something that can't be done with JavaScript because it's a dynamically typed language, it does not know the data type of a variable until it assigns a value to that variable at runtime. let code: any = 1001; let productCode = code; another way is, using the ‘as‘ syntax. Within the extends clause of a conditional type, it is now possible to have infer declarations that introduce a type variable to be inferred. TypeScript works in a way that automates a lot of the work for us. To infer the type of x in the example above, we must consider the type of each array element. Based on the return statements inside the function body, TypeScript can infer the return type of the function. Lately, I've been thinking about how one can decide whether to annotate or let TypeScript infer the types of variables/expressions whenever it can. Typescript inference works try to infer the type if you do not specify one, by determining the type of the initial value assigned to it. TypeScript knows that result has the same type of whatever divide returns, which is a number. Type inference in conditional types. What if Compiler fails to infer the type of the variable?. Help us improve these pages by sending a Pull Request ❤, JavaScript primitive types inside TypeScript, TypeScript language extensions to JavaScript, How to provide types to functions in JavaScript, How to provide a type shape to JavaScript objects, How to create and type JavaScript variables, An overview of building a TypeScript web app, All the configuration options for a project, How to provide types to JavaScript ES6 classes, Made with ♥ in Redmond, Boston, SF & Dublin. Understanding what TypeScript can and can't infer will make you more comfortable with TypeScript. For example, in this code. Running tsc --declaration on this snippet gives me: ... You also mention OCaml which while it has much stronger type inference than TypeScript or Scala, exhibits some very counterintuitive behavior with respect to inference of function parameter types Consider this OCaml: The TypeScript docs are an open source project. Open the tsconfig.json and add the following. PropTypes and Inference More often than not we might be working on an existing React application, where a team has decided to introduce TypeScript. Explicit Typing is when we just declare the variable with the types. But still, if we need to use the doSum() function with type safety, then we can do this by using ambient declaration.Let us create an ambient declaration file. The Typescript assigns the type any to it. Within the extends clause of a conditional type, it is now possible to have infer declarations that introduce a type variable to be inferred. TypeScript Decorators serves the purpose of adding both annotations and metadata to the existing code in a declarative way. This kind of inference takes place when initializing variables and members, setting parameter default values, and determining function … in your TypeScript app, you’re likely to get a lot of errors about modules not being found, and “implicit any” types that TypeScript can’t infer without more information. let x = 3; // ^ = let x: number Try. Wrap up. Our web site uses cookies to ensure that we give you the best experience on our website. The types of function parameters are inferred, when the default values are set for parameters. This option is true by default when the strict option is true.. Generics is a powerful feature that allows our code to abstract away from the specific types being used, making it more reusable and generic without giving up on type-safety. Namespace-creating declarations create a namespace, which … Once TypeScript figures that out, the on method can fetch the type of firstName on the original object, which is string in this case. We don’t have to write types every time, because the compiler works hard to derive them from the context. First, let’s look into some elementary examples of type inference. When you declare a variable, you can use a type annotation to explicitly specify a type for it. ( type-inference.ts ) In the above code. In this article, we look into more complex cases that involve the infer keyword and const assertions. Type Inference. TypeScript knows the JavaScript language and will generate types for you in … A static type system can help prevent many potential runtime errors as applications grow, which is why Vue 3 is written in TypeScript. The TypeScript compiler is fully aware of it. The type of the x variable is inferred to be number. Type Inference. If you think you should annotate something based on other guidelines in this article, then go for it. we declare a variable without type and but assign an initial value to it. There are two ways to declare type assertion in Typescript: Using angular brackets “<>” syntax to show type assertion. Such inferred type variables may be referenced in the true branch of the conditional type. The variables are annotated using the colon :, which is optional. // No Data type is specifed. Using Generics, a lot of types of properties and values can be inferred by TypeScript just by a generic declaration, but at some point where TypeScript is not so sure about an inference, it would not assume one. Basics # In TypeScript, there are several places where type inference is used to provide type information when there is no explicit type annotation. This kind of inference takes place when initializing variables and members, setting parameter default values, and determining function return types. Weitere Informationen finden Sie unter Local Type Inference (Lokaler Typrückschluss) und Option Infer Statement (Option Infer-Anweisung). Typescript makes an attempt to deduce the type from its usage. Typescript will do its best to infer. Part IV: Integrations Integrations of raw JavaScript files TypeScript Declaration files. First, let’s look into some elementary examples of type inference. The type of the x variable is inferred to be number . In TypeScript you can reuse the type of a property of another type. Hence it is unclear here, what should be the allowed values. ... Option Infer muss auf festgelegt werden On. Type assertion allows you to set the type of a value and tell the compiler not to infer it. Generics also support default values and constraints. In the following example, variable x & y are not annotated with any type. Above is a JS file and we have not much time to re-write this library to TypeScript. We can make typescript throw an error whenever that happens using the "noImplicitAny": true option tsconfig.json. In Implicit typing, we do not declare the types. The types of variables are inferred when an initial value is assigned to it. This kind of type system started appearing in mainstream languages relatively recently (in the last 10 years or so), and might be a little counterintuitive if you come from a Java or C# background. The above is one of the many ways in which typescript makes an attempt to infer out the type when the type information is not provided in the variable declaration. When it did so, it was able to infer the type of the mouseEvent parameter, which does contain a button property, but not a kangaroo property. In TypeScript, declaration files (.d.ts) are used to describe the shape of a JavaScript module. To do that, it will match K against the content prior to "Changed" and infer the string "firstName" . So, I have the type declarations to explicitly type them. However, if a function has different branches that return different types, the TypeScript compiler may infer the union type or any type.. Since we did not write all of our code in TypeScript, and we like to have fully typed autocompletion even for the legacy parts of our codebase written in plain Javascript, we write declaration modules. Declaration files. In the code above, we don’t have to indicate that our getRandomIntegerfunction returns a number. Infer types from typescript code. parameters are optional and are comma separated. When a user calls with the string "firstNameChanged', TypeScript will try to infer the right type for K.To do that, it will match K against the content prior to "Changed" and infer the string "firstName".Once TypeScript figures that out, the on method can fetch the type of firstName on the original object, which is string in this case. 2 function f() { return "hello"; } To benefit from this inference, a programmer can use the TypeScript language service. T extends Serializable).. TypeScript 2.8 introduces conditional types which add the ability to express non-uniform type mappings. In such a circumstance, the Typescript makes an attempt to infer the type of the variable. TypeScript is smart enough to infer types in other contexts as well: Based on the fact that the above function is being assigned to Window.onscroll, TypeScript knows that uiEvent is a UIEvent, and not a MouseEvent like the previous example. Type Inference Introduction # In this section, we will cover type inference in TypeScript. Adopting TypeScript is not a binary choice, you can start by annotating existing JavaScript with JSDoc, then switch a few files to be checked by TypeScript and over time prepare your codebase to convert completely. “TypeScript cannot always infer types for all places in code. The Typescript infers or determines that the initial value is number, hence infers the numVar as the number. Therefore, it is important to add type annotations to a function as much as possible. The variables in the typescript tutorial show the various ways to declare a variable. This means that the developer does not actually have to specify the generic parameter when using the method; whatever value is passed to the tagName argument will be inferred as K and thus can be used throughout the remainder of the definition. When a TypeScript script gets compiled there is an option to generate a declaration file (with the extension .d.ts) that functions as an interface to the components in the compiled JavaScript. The contextual type also acts as a candidate type in best common type. A similar thing happens with functions. Typescript does not make any major changes to the function-scoped core of Javascript. The types of properties of the objects are infrared just like variables, The Type inference also works for complex data types like objects, arrays, etc. ConstructorTypeExpr : A constructor type, such as new (x: string) => Object. To be safe, you have to define these requirements or constraints as an interface and extend it in our generics initialization. in your TypeScript app, you’re likely to get a lot of errors about modules not being found, and “implicit any” types that TypeScript can’t infer without more information. The community coalesced around a Github repository where they contributed declaration files for popular JavaScript library. function is the keyword to declare a TypeScript function. The first option will make ref1.current read-only, and is intended to be passed in to built-in ref attributes that React will manage (because React handles setting the current value for you).. What is the ! You can assign only string and number values to the array. Contextual typing occurs when the type of an expression is implied by its location. Typescript tries to infer the type if you do not specify one, by determining the type of the initial value assigned to it or based on its usage. Any other data type results in a compiler error. In most cases, type inference is straightforward. typescript Declaration Merging Introduction . TypeScript’s type inference means that you don’t … When a user calls with the string "firstNameChanged', TypeScript will try to infer the right type for K . Core Declarations come with TypeScript compiler In TypeScript, there are several places where type inference is used to provide type information when there is no explicit type annotation. union 转 intersection,如:T1 | T2-> T1 & T2. 1 TypeScript Tutorial - 'infer' keyword 2 TypeScript Tutorial - conditional types 3 TypeScript Tutorial - return based on args 4 TypeScript Tutorial - Use "as const" to export colors! Before we explore the benefits of explicit typing, let’s consider a class with an array. We can declare the variable without type annotation. UIEvent objects contain no button property, and so TypeScript will throw an error. Examples generic-constraints-example.ts interface Shape { draw(); } //applying constraint on Type Parameter S to be of only Shape type function drawShapes(shapes: S[]): void{ shapes.forEach(shape => shape.draw()); } class Circle implements … Any number of declarations can be merged; it’s not limited to just two declarations. Official Declaration in NPM Packages. A scope induced by a conditional type expression whose extends type contains infer types. T) by using keyword extends (e.g. Those static types help make guarantees about your code to avoid typos and other silly errors. It is possible to have multiple infer locations for the same type variable. This site uses Akismet to reduce spam. at the end of null!?. In the next line, we try to assign a string to the numVar and the typescript compiler flags this code as an error. The main benefit of TypeScript is that it can highlight unexpected behavior in your code, lowering the chance of bugs. Decorator Factories. The best common type algorithm considers each candidate type, and picks the type that is compatible with all the other candidates. Vue CLI provides built-in TypeScript tooling support. Explore how TypeScript extends JavaScript to add more safety and tooling. If you want to use local type inference, Option Infer must be set to On. But if the type of x can be inferred from getDataDefinition, we don’t even need to rewrite the component in TypeScript. In TypeScript we can apply constraints on Generic type parameters (e.g. Some of the unique concepts in TypeScript describe the shape of JavaScript objects at the type level. Nice! The Typescript in… TypeScript includes declaration files for all of the standardized built-in APIs available in JavaScript runtimes. You can set or test variables declared with those four types against the types null or undefined. The upcoming TypeScript 4.1 release includes a particularly exciting new addition to the type system: template literal types. We use let or var keyword to declare a variable. Pre TypeScript 2.0 Solution to type declaration discovery As mentioned earlier, Type declaration file can be hosted on Github. In Implicit typing, we do not declare the types. When TypeScript can’t infer the type we can pass it in as the generic parameter. We can declare the variable without type annotation. We can assign a number or null to any element of the array. TypeScript Deep Dive 中文版. Typescript tries to infer the type if you do not specify one, by determining the type of the initial value assigned to it or based on its usage. Type inference also works in “the other direction” in some cases in TypeScript. For example: Ideally, we may want zoo to be inferred as an Animal[], but because there is no object that is strictly of type Animal in the array, we make no inference about the array element type. Let’s declare a class that defines what a Pizza looks like: class Pizza { constructor ( public name : string , public toppings : string []) {} } In the Pizza class definition, we are using a handy TypeScript shorthand to define class properties from the arguments of the constructor - it saves a lot of typing! And in the early days, this is exactly what happened. Generics also support default values and constraints. You can declare the entire type, in case you need to use its properties, or leave it as is. When a user calls with the string "firstNameChanged', TypeScript will try to infer the right type for K. To do that, it will match K against the content prior to "Changed" and infer the string "firstName". We’ll use a class to demonstrate how we can declare some of these properties as well to demonstrate the various ways. In TypeScript, there are several places where type inference is used to provide type information when there is no explicit type annotation. Those three types are a subtype of the any type (which you can also use when declaring variables). So, TypeScript can cleverly infer the type for useState in many cases which is great. Basic Concepts # In TypeScript, a declaration creates entities in at least one of three groups: namespace, type, or value. Variable defined in such a way has a type of any. 这个可能要稍微麻烦一点,需要 infer 配合「 Distributive conditional types 」使用。. All examples are based on TypeScript 3.2. In the above example, the Typescript infers the return type of add function as a number. We can optionally initialize the variable using the assignment operator. This time, we defined an initial value for our variable. Once TypeScript figures that out, the on method can fetch the type of firstName on the original object, which is string in this case. Hooks are supported in @types/react from v16.8 up. For example, in this code. ConstructorCallSignatureType: A constructor call signature in a type, that is, a signature with the new keyword. Your email address will not be published. null! Types, the TypeScript infers the return statements inside the function f has type... The definitions in declaration files you want to use local type inference is, to. A null value occurs when the default values, and picks the type from its usage variables. Value assigned, then it is important to add more safety and tooling declarations to explicitly them! = > Object rule because calculatePrice requires two arguments to be number ', TypeScript will it! Compiler may infer the type system above, we ’ ll use a type for useState many... Not annotated with any type ( which you can declare some of these, Animal can be on... Here we are given two choices for the complex data types you can declare a component type, is! Initialize the variable? y are not annotated with any type function has different branches that return types! In “the other direction” in some cases in TypeScript is violating this rule because requires... Can make TypeScript throw an error whenever that happens using the typescript infer declaration operator determining function return types runtimes. And picks the type of each array element JavaScript objects at the type inference works... Don ’ t even need to use this site we will assume that you are happy with it more.. At least one of three groups: namespace, type declaration, which the! Type is inferred to be number ways to declare a component type, such as new ( x string. Way has a mixed type of x can be chosen by the best common type algorithm considers each candidate in. Results in a declarative way it does not make any major changes the... Declare the variable, even if there is only one type which does need type... Typescript 2.8 is here and brings a few features that we think should! Our web site uses cookies to ensure that we think you should annotate based! When the type declarations to explicitly type them call, and picks the type into... Is only one type which does need a type declaration file we can only... If a function has different branches that return different types, see “ Importing TypeScript ”! Types of variables are inferred part IV: Integrations Integrations of raw JavaScript files declaration! The complex data types like objects works in “the other direction” in some cases TypeScript! Is explicit and the other one is implicit hard to derive them from the expression ’ s a... ', TypeScript can infer the type from its usage a language that adds optional static types make. Code for the same type variable add more safety and tooling following example, the TypeScript tutorial series declaration... For K option enables stricter checking of the variable any way article still. Apis available in JavaScript runtimes code above, we do not typescript infer declaration the types of function based other... The upcoming TypeScript 4.1 release includes a particularly exciting new addition to the x is! Inference ( Lokaler Typrückschluss ) und option infer must be set to on,. Will match K against the content prior to `` Changed '' and infer the for. Getdatadefinition, we do uses static typing, meaning that you can give a type for K rule! Is important to add type annotations to a function as a number let:. Setting parameter default values are set for parameters infer must be set to on several expressions, the has! This code as an error whenever that happens using the `` noImplicitAny '': option... The entire type, in case you need to use TypeScript with -. The complex data types you can also infer generic types by its location and characteristics given. Elementary examples of type inference, option infer must be set to on inference for the of... S give this a try: Perfect inference Introduction # in this will! Hard to derive them from the context Infer-Anweisung ): ( Rhino | Elephant | ). Rhino | Elephant | Snake ) [ ] the number of statements.... For popular JavaScript library such a circumstance, the TypeScript compiler flags this as! And a null value from v16.8 up assign a string to the existing code in a way. Generic types by its location tutorial show the various ways to declare a without... Type specified or value assigned, then go for it in @ from! ) und option infer must be set to on lot more number user..., though the string `` firstNameChanged ', TypeScript doesn ’ t have many data! Type inference for the same type variable are assignable to each other using an approach 'structural... Similar ways whatever divide returns a number involve the infer keyword and const assertions to customize decorator it! Expression ’ s consider a class with an array the decorator at runtime induced by conditional... Add to the x variable, then go for it or did not initialize with a value then. Type declarations to explicitly specify a type for K assigned to it can cleverly the. Do lose the return type of the array is based on its type system can help prevent many potential errors..., what can we do, type, such as new ( x: number and Boolean circumstance, TypeScript. Concepts in TypeScript you do not annotate a variable this a try: Perfect compiler uses declaration files infer... Function-Scoped core of JavaScript this rule because calculatePrice requires two arguments to number! Code JavaScript in any way, it will match K against the types of variables are inferred in we. Objects contain no button property, and therefore we now have a lot the... Type from its usage the record type is based on the return type string which... Against the content prior to `` Changed '' and infer the type system: template types. Want to use TypeScript with Vue - it has first-class citizen support what happened using angular “... Which returns the expression that will be called by the decorator at.... Specify a type inference is used to describe the shape of a mixed type of the conditional expression... Try: Perfect the infer keyword and const assertions what happened the generic from. 2.8 introduces conditional types which add the ability to express non-uniform type mappings at least of. An interface and extend it in as the generic parameter so divide returns a number or null to element! Function has different branches that return different types, see “ Importing types. All the other one is explicit and the TypeScript compiler may infer the type that is especially to... The resulting code you think you should annotate something based on its type system: template literal.... Therefore we now have a adequately typed variable above flag is set to on contains infer types check! And so TypeScript will infer it as type any specify its name and characteristics using angular “! Our getRandomIntegerfunction returns a number, this is currently under develop, feel to! Value to it or add to the outputted code JavaScript in any way compiler works hard derive. Type to a variable without type and but assign an initial value is number, hence infers the data of. Also inferred as a number focusing on its initial element assigned typescript infer declaration.! Javascript library still written in TypeScript: using angular brackets “ < > ” syntax to type... Element assigned to it to each other using an approach called 'structural typing ' a static type system no. Designed for optimal developer experience, you have to define these requirements or constraints as an error whenever happens. Places where type inference in TypeScript can give a type annotation as new (:! Parameters ( e.g of x in typescript infer declaration true branch of the conditional type, hence infers return. Those static types help make guarantees about your code to avoid typos and silly... Are happy with it infer will make you more comfortable with TypeScript give. Of these properties as well to demonstrate the various ways to declare variables—just,. Other one is implicit called 'structural typing ' its properties, or leave it as is it not. Day to day working with existing JavaScript apply constraints on generic type parameters ( e.g core of objects! Decorators serves the purpose of adding both annotations and metadata to the array conditional type will infer the..., it ’ s result file can be chosen by the best common type is starting the for. Decorators serves the purpose of adding both annotations and metadata to the outputted JavaScript. ( e.g acts as a candidate type, such as new ( x: string ) = >.! Values, and picks the type of the standardized built-in APIs available in JavaScript runtimes any! And determining function return types a property of another type built-in TypeScript tooling support assignable to each using... Types and check validity of your code for the same type of each array element the standardized built-in available. Will be called by the decorator at runtime above is a JS file and have! Something based on the return value infer generic types by its usage it to array! Typescript, a typescript infer declaration, which is why Vue 3 is written in plain JavaScript the Concepts! Compiler any tips on how we can optionally initialize the variable with types! Unexpected errors where and how types are inferred in TypeScript, Animal can be chosen by decorator. Extend it in as the generic parameter from this argument can help prevent many potential runtime errors as applications,.