Angular – Preview Image before Saving it

I came across a few samples of how to preview an image before saving it. So he’s my version “Angularfied”!

Here’s the app.component.ts (obviously move as you wish!)

import { Component } from '@angular/core';
 
@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  // This is our callback to get the URL out of the onload function
  private  urlPointer: (name: string) => void;
 
  // Our temp url value
  url: string;
 
  /*
    loadFileTest triggered by (change)='loadFileTest($event)' in the html
  */
  loadFileTest(event) {
    this.getFileForPreview(event.target, this.urlPointer = (url) => this.setLocalURL(url));
  }
 
  /*
    getFileForPreview
    fileInput - event.target from the change event
    callbackFunction - pointer to our callback function (setLocalURL)
  */
  getFileForPreview(fileInput, callbackFunction) {
    const reader = new FileReader();
    reader.onload = function(){
      // setLocalURL with reader.result (a string)
      callbackFunction(reader.result);
    };
    // This is what actually creates our URL
    reader.readAsDataURL(fileInput.files[0]);
  }
 
  setLocalURL(url: string) {
    // Our call back function which gets the url and saves it to our url variable
    this.url = url;
  }
}

Then we just need to add the following HTML

<input type='file' accept='image/*' (change)='loadFileTest($event)'><br>
<img id='output' src='{{ url }}'>

As easy as that! 🙂

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