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typescript18

[TypeScript] Decorators Decorators are a stage 2 proposal for JavaScript and are available as an experimental feature of TypeScript. So you should set the feature in your tsconfig.js. { "compilerOptions": { "target": "es5" "experimentalDecorators": true ... } } A decorator is a special kind of declaration that can be attached to a class declaration, method, accessor, property, or parameter. Decorators use the form @exp.. 2020. 10. 24.
[TypeScript] Iterators and Generators Iterator is a behavioral design pattern that allows sequential traversal through a complex data structure without exposing its internal details. Generator is a lazy iterator. Iterables An object is deemed iterable if it has an implementation for the Symbol.iterator property. Some built-in types like Array, Map, Set, String, Int32Array, Uint32Array, etc. have their Symbol.iterator property alread.. 2020. 10. 23.
[TypeScript] Interface TypeScript's type checking focuses on the shape that values have. This is called 'duck typing' or 'structural subtyping'. In TypeScript, interfaces fill the role of naming these types and are a powerful way of defining contracts within code as well as contracts with code outside of the project. interface IToDoItem { text: string; isCompleted: boolean } function addItem(item: IToDoItem) { console.. 2020. 10. 17.
[TypeScript] Destructuring and Spread Array Destructuring let input = [1, 2]; let [first, second] = input; console.log(`${first}, ${second}`); // 1, 2 Multiple values of an array can be easily assigned as variables. function f([first, second]: [number, number]) { console.log(`${first}, ${second}`); } f([1, 2]) // 1, 2 It can be also applied in the parameters of a function. let [first, ...rest] = [1, 2, 3, 4]; console.log(first); // .. 2020. 10. 16.
[TypeScript] Variable Declaration (var, let, const) var Declarations Declaring a variable in JavaScript has always traditionally been done with the var keyword. (ES5) var num = 7; Scoping Rules It is not an error to declare the same variable multiple times with var. var num = 7; var num = 3; let Declarations let differs from var in point of semantics. let say = "Hello"; Block Scoping Unlike variables declared with var whose scopes leak out to the.. 2020. 10. 15.
[TypeScript] Dev. Environment Configuration with VS Code TypeScript is a typed superset of JavaScript that compiles to plain JavaScript. It offers classes, modules, and interfaces to help you build robust components. Installation NPM Module If you want to use TypeScript compiler wherever, install it globally. $ yarn globally add typescript or $ npm i -g typescript If you want to use TypeScript only in a specific project, you can install it locally. $ .. 2020. 10. 12.