domdumont / typescript2-cheatsheet

My personal cheat sheet for Typescript 2

Typescript2-CheatSheet

My personal cheat sheet for Typescript 2

Exports

• everything can be exported

    export interface StringValidator
    export const numberRegexp
    export class ZipCodeValidator 

• exports can be renamed

export { ZipCodeValidator as mainValidator };

• You can export something without importing it on your own

export {ZipCodeValidator as RegExpBasedZipCodeValidator} from "./ZipCodeValidator";

Imports

• You can import a single export

import { ZipCodeValidator } from "./ZipCodeValidator";

• you can rename an import

import { ZipCodeValidator as ZCV } from "./ZipCodeValidator";

• you can import an entire module

import * as validator from "./ZipCodeValidator";
let myValidator = new validator.ZipCodeValidator();

• take care of default export. Import is different and act as a rename. Below import num is the same thing as import default as num.

export default "123";

import num from "./OneTwoThree";
console.log(num); // "123"

Properties getter/setter

private _timeInterval: number;

get timeInterval(): number {
    return this._timeInterval;
}
 
set timeInterval(value: number) {
    if (value === undefined) throw 'Please supply time interval';
    this._timeInterval = value;
}

Instantiate interface

Instead of

this.model = Object(); // initialize this to an empty object

Do this :

this._models = <IModels> {};

Instantiate empty object and then add properties dynamically

    var opts:any = {}
    opts.jwtFromRequest = ExtractJwt.fromAuthHeader();
    opts.secretOrKey = 'config.secret';

Singleton

private static instance: MyClassName;

static getInstance() {
        if (!MyClassName.instance) {
            MyClassName.instance = new MyClassName();
            // ... any one time initialization goes here ...
        }
        return MyClassName.instance;
    }

Get/Set/accesors/property

get Text():string {

}

set Text(value:string) {
}

Tips for importing JS without having types for it

declare const foo: any;