Load image from url and draw to HTML5 Canvas

In case you want a Promise version instead of the onload approach:

async function drawImage(url, ctx) {
  let img = new Image();
  await new Promise(r => img.onload=r, img.src=url);
  ctx.drawImage(img, 0, 0);
}

let ctx = document.querySelector("#myCanvas").getContext("2d");
await drawImage("https://example.com/image.png", ctx);

Easy as this...

var img=new Image();
img.onload=start;
img.src="myImage.png";
function start(){
    ctx.drawImage(img,0,0);
}

Simple, just create an image object in JavaScript, set the src, and wait for the load event before drawing.

Working Example:

var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
var img = new Image();
img.onload = function() {
    ctx.drawImage(img, 0, 0);
};
img.src = 'https://cdn.sstatic.net/stackexchange/img/logos/so/so-icon.png';

<canvas id="myCanvas"></canvas>