I decided to update my TypeScript brush plugin for TypeScript 3.0 and also to specify it works with latest WordPress 4.9.8. The plugin page on WordPress.org is located here – https://wordpress.org/plugins/syntax-highlighter-evolved-typescript/changelog/
let foo: unknown = 10; // Since `foo` has type `unknown`, TypeScript // errors on each of these locations. foo.x.prop; foo.y.prop; foo.z.prop; foo(); new foo(); upperCase(foo); foo `hello world!`; function upperCase(x: string) { return x.toUpperCase(); }
// TODO (billg): 5 overloads should *probably* be enough for anybody? function call<T1, T2, T3, T4, R>(fn: (param1: T1, param2: T2, param3: T3, param4: T4) => R, param1: T1, param2: T2, param3: T3, param4: T4): R function call<T1, T2, T3, R>(fn: (param1: T1, param2: T2, param3: T3) => R, param1: T1, param2: T2, param3: T3): R function call<T1, T2, R>(fn: (param1: T1, param2: T2) => R, param1: T1, param2: T2): R function call<T1, R>(fn: (param1: T1) => R, param1: T1): R; function call<R>(fn: () => R, param1: T1): R; function call(fn: (...args: any[]) => any, ...args: any[]) { return fn(...args); }
export interface Props { name?: string } export class Greet extends React.Component<Props> { render() { const { name } = this.props; // Notice the `!` ------v return <div>Hello ${name!.toUpperCase()}!</div>; } static defaultProps = { name: "world"} }
function loudlyGreet(name = "world") { // Thanks to the default initializer, `name` will always have type `string` internally. // We don't have to check for `undefined` here. console.log("HELLO", name.toUpperCase()); } // Externally, `name` is optional, and we can potentially pass `undefined` or omit it entirely. loudlyGreet(); loudlyGreet(undefined);
// Some non-TypeScript JSX file import * as React from "react"; import * as ReactDOM from "react-dom"; export class Greet extends React.Component { render() { const { name } = this.props; return <div>Hello ${name.toUpperCase()}!</div>; } static defaultProps = { name: "world", }; } // Notice no `name` attribute was specified! // vvvvvvvvv const result = ReactDOM.renderToString(<Greet />); console.log(result);
import * as _foo from "foo"; export async function bar() { let foo: typeof _foo = await import("foo"); }
function useKey<T, K extends Extract<keyof T, string>>(obj: T, k: K) { let propName: string = k; // ... }