Joshua Joshua - 6 months ago 342
Javascript Question

Angular 2 typescript invoke javascript function

Is there a correct way to invoke a JavaScript function from a component in Angular 2 (TypeScript) ?

Here is my component :

import { ElementRef, AfterViewInit } from '@angular/core';

export class AppComponent implements AfterViewInit {

constructor(private _elementRef: ElementRef) {
}

ngAfterViewInit() {
/**
* Works but i have this error :
* src/app.component.ts(68,9): error TS2304: Cannot find name 'MYTHEME'.
* src/app.component.ts(69,9): error TS2304: Cannot find name 'MYTHEME'.
*/
MYTHEME.documentOnLoad.init();
MYTHEME.documentOnReady.init();

/**
* Works without error, but doesn't seem like a right way to do it
*/
var s = document.createElement("script");
s.text = "MYTHEME.documentOnLoad.init(); MYTHEME.documentOnReady.init();";
this._elementRef.nativeElement.appendChild(s);
}
}


Calling the JavaScript function directly result in an compilation error, but the syntax in the "compiled" JavaScript file (app.component.js) is correct :

AppComponent.prototype.ngAfterViewInit = function () {
MYTHEME.documentOnLoad.init();
MYTHEME.documentOnReady.init();
};


The 2nd way (appendChild) works without error, but i don't think (altering the DOM from typescript/angular) is the correct way to do it.

I found this : Using a Javascript Function from Typescript I tried declaring the interface :

interface MYTHEME {
documentOnLoad: Function;
documentOnReady: Function;
}


But the TypeScript doesn't seem to recognize it (no error in the interface declaration).

Thanks

Edit :

Following the answer by Juan Mendes this is what i ended with :

import { AfterViewInit } from '@angular/core';

interface MYTHEME {
documentOnLoad: INIT;
documentOnReady: INIT;
}
interface INIT {
init: Function;
}
declare var MYTHEME: MYTHEME;

export class AppComponent implements AfterViewInit {

constructor() {
}

ngAfterViewInit() {
MYTHEME.documentOnLoad.init();
MYTHEME.documentOnReady.init();
}
}

Answer

You have to tell TypeScript about external (JavaScript) declarations using declare. See https://www.typescriptlang.org/docs/handbook/writing-declaration-files.html

interface MyTheme {
    documentOnLoad: Function;
    documentOnReady: Function;
}
declare var MYTHEME: MyTheme;

Or anonymously

declare var MYTHEME: {documentOnLoad: Function, documentOnReady: Function};