Is key-value pair available in Typescript? Yes. Called an index signature: interface Foo { [key: string]: number; } let foo:Foo = {}; foo[‘hello’] = 123; foo = { ‘leet’: 1337 }; console.log(foo[‘leet’]); // 1337 Here keys are string and values are number. More You can use an es6 Map for proper dictionaries, polyfilled by core-js.
There isn’t any semantic difference There is no difference at all. Type[] is the shorthand syntax for an array of Type. Array<Type> is the generic syntax. They are completely equivalent. The handbook provides an example here. It is equivalent to write: function loggingIdentity<T>(arg: T[]): T[] { console.log(arg.length); return arg; } Or: function loggingIdentity<T>(arg: Array<T>): Array<T> … Read more
This can be set up on your tsconfig.json file, as it is a TS feature. You can do like this: “compilerOptions”: { “baseUrl”: “src”, // This must be specified if “paths” is. … “paths”: { “@app/*”: [“app/*”], “@config/*”: [“app/_config/*”], “@environment/*”: [“environments/*”], “@shared/*”: [“app/_shared/*”], “@helpers/*”: [“helpers/*”] }, … Have in mind that the path where you … Read more
Actually, there appears to now be a simple way. The following code works in TypeScript 1.5: function sayName({ first, last=”Smith” }: {first: string; last?: string }): void { const name = first + ‘ ‘ + last; console.log(name); } sayName({ first: ‘Bob’ }); The trick is to first put in brackets what keys you want … Read more
UPDATE: Looks like the question title attracts people looking for a union of all possible property value types, analogous to the way keyof gives you the union of all possible property key types. Let’s help those people first. You can make a ValueOf analogous to keyof, by using indexed access types with keyof T as … Read more
TypeScript 2.4 Now has string enums so your code just works: enum E { hello = “hello”, world = “world” }; 🌹 TypeScript 1.8 Since TypeScript 1.8 you can use string literal types to provide a reliable and safe experience for named string values (which is partially what enums are used for). type Options = … Read more
Problem statement Problem occurs when we want to import CommonJS module into ES6 module codebase. Before these flags we had to import CommonJS modules with star (* as something) import: // node_modules/moment/index.js exports = moment // index.ts file in our app import * as moment from ‘moment’ moment(); // not compliant with es6 module spec … Read more
This behaviour is controlled by the following option: Settings/Preferences Editor | Code Style | TypeScript “Punctuation” tab | Generated code -> Quote marks As of 2017.1 version it’s on new Punctuation tab and options are named a bit differently:
In your settings (either user or workspace) there is a setting that you can tweak to hide anything you’d like: { “files.exclude”: { “**/.git”: true, “**/.DS_Store”: true } } So you can add in the following to hide .js and .js.map files “**/*.js”: true, “**/*.js.map”: true As this other answer explains, most people probably only … Read more
Updated 07/12/2016: Typescript 2.1 introduces Mapped Types and provides Partial<T>, which allows you to do this…. class Person { public name: string = “default” public address: string = “default” public age: number = 0; public constructor(init?:Partial<Person>) { Object.assign(this, init); } } let persons = [ new Person(), new Person({}), new Person({name:”John”}), new Person({address:”Earth”}), new Person({age:20, … Read more