Image not showing up when using drawImage() from canvas rendering context 2D

Need help with drawImage() method in JavaScript

<head>
</head>
<body>
    <script type = "text/javascript">
        var body, canvas, img, cxt;
        body = document.getElementsByTagName("body")[0];
        
        canvas = document.createElement("canvas");
        canvas.style.width = "1000px";
        canvas.style.height = "500px";
        body.appendChild(canvas);
        img = document.createElement("img");
        cxt = canvas.getContext("2d");
        img.onload = function () {
            cxt.drawImage(img,0,0,1000,500,0,0,1000,500);

        }

        img.src = "/clouds.png";
    </script>
</body>

Answer №1

It is important to ensure that your code executes after the DOM has finished loading. Attempting to append elements to the body before it exists can cause errors.

To address this issue, you should enclose your code in a block that will be executed once the DOM is ready or when the entire window's content has been fully loaded:

See an Example Here

window.addEventListener("load", function () {
    var body, canvas, img, ctx;
    body = document.getElementsByTagName("body")[0];

    canvas = document.createElement("canvas");
    canvas.style.width = "500px";
    canvas.style.height = "400px";
    body.appendChild(canvas);
    
    img = document.createElement("img");
    ctx = canvas.getContext("2d");
    
    img.onload = function () {
        ctx.drawImage(img, 0, 0, 500, 400, 0, 0, 350, 200);
    }
    
    img.src = "http://cdn.sstatic.net/stackoverflow/img/<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="35544545595018415a40565d185c565a5b75">[email protected]</a>?v=fde6657a82e6";
});

Answer №2

One portion of the image I utilized happened to be white, which coincidentally was also the area that got cropped.

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