Angular2 innerHTML removes property, help needed t

问题:

I simply need to inject HTML in a div with id "main-wrapper", so in my component.ts i am using this code

    import { Component, OnInit, ElementRef,Renderer2,Inject } from '@angular/core';
    import { Pipe } from '@angular/core';
    import { DomSanitizer, SafeHtml, SafeStyle, SafeScript, SafeUrl, SafeResourceUrl } from '@angular/platform-browser';

    @Component({
      selector: 'app-editsection',
      templateUrl: './editsection.component.html',
      styleUrls: ['./editsection.component.css']
    })

    export class EditsectionComponent implements OnInit {
    ...//some code

    constructor(
        @Inject(DOCUMENT) private document: any,
        private route: ActivatedRoute,
      private elRef: ElementRef,
      private el: ElementRef,
      private _sanitizer:DomSanitizer
      ) { }

    ngOnInit() {
    var strHTML = '<p>abc<p>';
     this.document.getElementById("main-wrapper").innerHTML += this._sanitizer.bypassSecurityTrustHtml(strHTML);

    ...
    }
    }

When i run the code it says: SafeValue must use [property]=binding: abc

(see http://g.co/ng/security#xss)

Why i need to implement this- Because when i am injecting innerHTML, i am loosing a property contenteditable="true"

Before applying innerHTML, my code looks as shown below:

<h1 _ngcontent-c2 contenteditable="true">Hii<h2>

After applying innerHTML it becomes:

<h1 _ngcontent-c2>Hii<h2>

Please help me resolve the problem

回答1:

The whole methodology behind angular is anchored on reduction of DOM manipulation via script (such as what you have) as recommended in http://angularjs.blogspot.com.au/2016/04/5-rookie-mistakes-to-avoid-with-angular.html.

There are very few circumstances where manipulating the DOM directly is necessary. Angular 2 provides a set of powerful, high-level APIs like queries that one can use instead. Leveraging these APIs confers a few distinct advantages

...

When you manipulate the DOM manually, you miss out on these advantages and ultimately end up writing less expressive code.

---

So instead of using this: this.document.getElementById("main-wrapper").innerHTML +=

You should make use of the templating engine / structural directives like *ngFor *ngIf inherent in angular.

// .html
<div class="main-wrapper"><p *ngIf="showabc">abc</p></div>
// .ts
var showabc: Boolean = true;

---

As per your comment:

You are loading a bunch of html from localstorage. In this case, you will have to manipulate the DOM. Ideally i would recommend re-configuration of this architecture for performance purposes as stated in the aformentioned.

1st, load the html into typescript...

public possibleHTML: Array; 
constructor(private sanitizer: DomSanitizer){}
ngOnInit(){  
   this.possibleHTML = loadContentFromLocalStorage();
   this.possibleHTML = this.possibleHTML.map(value => this.sanitizer.bypassSecurityTrustHtml(value));
}

2nd insert the html.

<div class="main-wrapper">
    <content *ngIf="possibleHTML">
       <div *ngFor="let html of possibleHTML">
           <div *ngIf="html.makevisible" [innerHtml]="html"></div>
       </div>
    </content>
</div>

drawbacks: css styling does not take effect unless it is defined as a global stylesheet styles.css instead of editsection.component.css.