How to get HTTP status code of <img> tags

Question

I have a page with a lot of images that are generated server-side depending on user actions. And when image loads successfully I'm happy, but when there is an error on the server I have to act according to what an error occurred.

For example:

• 500 code: do this stuff.
• 503 code: do that stuff

and so on.

So, my question: is there any way to get status code within "img" tag on-error event handler?

Answer 1

You may combine the couple technics to get img.status:

<img src="/no.img" onerror="error(this)">

function error(img) {
   var r = makeXMLHttpRequestAgain(img.src);
   if (r.status === 500) img.src = '/e500.img';
   if (r.status === 503) img.src = '/e503.img';
}

Answer 2

 function loadBinaryImageAndInsertToImgTag(imgElement, imageUrl) {
        let xhr = getXMLHttpRequest();
        xhr.onreadystatechange = ProcessResponse;
        xhr.open("GET", imageUrl, true);
        xhr.overrideMimeType('text/plain; charset=x-user-defined');
        xhr.send(null);

        function getXMLHttpRequest() {
            let xhr = null;

            if (window.XMLHttpRequest || window.ActiveXObject) {
                if (window.ActiveXObject) {
                    try {
                        xhr = new ActiveXObject("Msxml2.XMLHTTP");
                    } catch (e) {
                        xhr = new ActiveXObject("Microsoft.XMLHTTP");
                    }
                } else {
                    xhr = new XMLHttpRequest();
                }
            } else {
                alert("Your browser does not support XMLHTTP");
                return null;
            }
            return xhr;
        }

        function ProcessResponse() {
            if (xhr.readyState === 4) {
                if (xhr.status === 200) {
                    imgElement.src = "data:image/jpeg;base64," + encode64(xhr.responseText);
                    imgElement.style.display = "";
                } else {
                    alert("Error retrieving data!");
                }
            }
        }

        function encode64(inputStr) {
            let b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
            let outputStr = "";
            let i = 0;

            while (i < inputStr.length) {
                let byte1 = inputStr.charCodeAt(i++) & 0xff;
                let byte2 = inputStr.charCodeAt(i++) & 0xff;
                let byte3 = inputStr.charCodeAt(i++) & 0xff;
                let enc1 = byte1 >> 2;
                let enc2 = ((byte1 & 3) << 4) | (byte2 >> 4);
                let enc3, enc4;
                if (isNaN(byte2)) {
                    enc3 = enc4 = 64;
                }
                else {
                    enc3 = ((byte2 & 15) << 2) | (byte3 >> 6);
                    if (isNaN(byte3)) {
                        enc4 = 64;
                    }
                    else {
                        enc4 = byte3 & 63;
                    }
                }
                outputStr += b64.charAt(enc1) + b64.charAt(enc2) + b64.charAt(enc3) + b64.charAt(enc4);
            }
            return outputStr;
        }
    }

Answer 3

You cannot check HTTP status this way. However you can check if image was loaded or not using naturalWidth property.

if (img.naturalWidth === 0) {
    // do sth
}

Hope it help.