JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/1.7.17/fabric.min.js"></script>
<canvas id="c1">

</canvas>

JavaScript

var canvas = new fabric.Canvas('c1');
 canvas.setWidth(800);
 canvas.setHeight(800);
 var canvasHeight = canvas.height;
 var canvasWidth = canvas.width;

 //Just a debug statement console.log(canvasWidth, canvasHeight);

 var bgImg = new fabric.Image();
 bgImg.setSrc('http://www.aamcocolorado.com/images/Highway-Traffic.jpg', function () {
   bgImg.set({
      top: 0,
      left: 0,
      scaleX: canvasWidth/bgImg.width,
      scaleY: canvasHeight/bgImg.height,
   });
 });

 canvas.setBackgroundImage(bgImg);