Adding script tags in Angular component template

问题:

Angular2 removes <script> tags automatically from templates to stop people using this functionality as a "poor's man" loader.

The issue here is that script tags currently have more uses than just loading code or other script files. There is the possibility that further functionality around <script> tags will be introduced in future as well.

One current use is JSON-LD which takes the format

<script type="application/ld+json">
{
    "@context":"http://schema.org",
    "@type":"HealthClub",
    ...
}
</script>

A commonly suggested work around is to dynamically add script tags to the document via the ngAfterViewInit hook, but this is obviously not proper ng2 practice and will not work server side, which JSON-LD obviously needs to be able to do.

Are there any other workarounds that we can use to include <script> tags in angular2 templates (even if the tag is inert within the browser) or is this a case of the framework being too opinionated? What other solutions might exist if this situation can't be solved in angular2?

回答1:

Maybe a little late to the party here, but since the above answers do not work well with Angular SSR (e.g. document is not defined server-side or document.createElement is not a function), I decided to write a version that works for Angular 4+, in both server and browser context:

Component Implementation

import { Renderer2, OnInit, Inject } from '@angular/core';
import { DOCUMENT } from '@angular/common';

class MyComponent implements OnInit {

    constructor(
        private _renderer2: Renderer2, 
        @Inject(DOCUMENT) private _document: Document
    ) { }

    public ngOnInit() {

        let script = this._renderer2.createElement('script');
        script.type = `application/ld+json`;
        script.text = `
            {
                "@context": "https://schema.org"
                /* your schema.org microdata goes here */
            }
        `;

        this._renderer2.appendChild(this._document.body, script);
    }
}

Service Implementation

NOTE: Services cannot use Renderer2 directly. In fact, rendering an element is supposed to be done by a Component. However, you might find yourself in situation where you want to automate the creation of JSON-LD script tags on a page. As an example, a situation could be to invoke such function on route navigation change events. Hence I decided to add a version that works in a Service context.

import { Renderer2, Inject } from '@angular/core';
import { DOCUMENT } from '@angular/common';

/**
 * Use a Service to automate creation of JSON-LD Microdata.
 */
class MyService {

    constructor(
        @Inject(DOCUMENT) private _document: Document
    ) { }

    /**
     * Set JSON-LD Microdata on the Document Body.
     *
     * @param renderer2             The Angular Renderer
     * @param data                  The data for the JSON-LD script
     * @returns                     Void
     */
    public setJsonLd(renderer2: Renderer2, data: any): void {

        let script = renderer2.createElement('script');
        script.type = 'application/ld+json';
        script.text = `${JSON.stringify(data)}`;

        renderer2.appendChild(this._document.body, script);
    }
}

回答2:

There is no Angular2 way of adding a script tag to a template.

Using require(...) to load external scripts from the components class was mentioned as a workaround (haven't tried it myself)

To dynamically add a script tag use

constructor(private elementRef:ElementRef) {};

ngAfterViewInit() {
  var s = document.createElement("script");
  s.type = "text/javascript";
  s.src = "http://somedomain.com/somescript";
  this.elementRef.nativeElement.appendChild(s);
}

See also angular2: including thirdparty js scripts in component

回答3:

The following works with Angular 5.2.7:

The required imports are:

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

Implement AfterViewInit:

export class HeroesComponent implements AfterViewInit {

If your component is implementing more that one interfaces, separate them by comma; for example:

export class HeroesComponent implements OnInit, AfterViewInit {

Pass the below arguments to constructor:

constructor(@Inject(DOCUMENT) private document, private elementRef: ElementRef) { }

Add ngAfterViewInit method of view life-cycle:

ngAfterViewInit() {
    const s = this.document.createElement('script');
    s.type = 'text/javascript';
    s.src = '//external.script.com/script.js';
    const __this = this; //to store the current instance to call 
                         //afterScriptAdded function on onload event of 
                         //script.
    s.onload = function () { __this.afterScriptAdded(); };
    this.elementRef.nativeElement.appendChild(s);
  }

Add afterScriptAdded member function.

This function will be called after the external script is loaded successfully. So the properties or functions you want to use from external js will be accessed in the body of this function.

 afterScriptAdded() {
    const params= {
      width: '350px',
      height: '420px',
    };
    if (typeof (window['functionFromExternalScript']) === 'function') {
      window['functionFromExternalScript'](params);
    }
  }

回答4:

Actually There is no Angular2 way of adding a script tag to a template. but you can do some trick first of all you will import AfterViewInit and ElementRef from angular2 like this :

import {Component,AfterViewInit,ElementRef} from 'Angular2/core';

then you will you will implement them in your class like that :

export class example1 implements AfterViewInit{}

and here is a very simple javascript dom trick you gonna do

 export class example1 implements AfterViewInit{
 ngAfterViewInit()
 {
  var s=document.createElement("script");
  s.type="text/javascript";
  s.innerHTML="console.log('done');"; //inline script
  s.src="path/test.js"; //external script
 }
}

回答5:

const head = document.getElementsByTagName('head')[0];
const _js = document.createElement('script');
_js.type = 'text/javascript';
_js.appendChild(document.createTextNode('{your js code here}'));
head.appendChild(_js);

this can be placed anywhere one wishes and it's a good approach