Script to convert image into base64, using xhr2 without canvas. Therefore it is possible to convert images from another domains, using CORS.

getBase64FromImage.js

function getBase64FromImage(url, onSuccess, onError) {
    var xhr = new XMLHttpRequest();
 
    xhr.responseType = "arraybuffer";
    xhr.open("GET", url);
 
    xhr.onload = function () {
        var base64, binary, bytes, mediaType;
 
        bytes = new Uint8Array(xhr.response);
        //NOTE String.fromCharCode.apply(String, ...
        //may cause "Maximum call stack size exceeded"
        binary = [].map.call(bytes, function (byte) {
            return String.fromCharCode(byte);
        }).join('');
        mediaType = xhr.getResponseHeader('content-type');
        base64 = [
            'data:',
            mediaType ? mediaType + ';':'',
            'base64,',
            btoa(binary)
        ].join('');
        onSuccess(base64);
    };
    xhr.onerror = onError;
    xhr.send();
}

Didn't work for me, still getting CORS related warnings.

Didn't work for me, still getting CORS related warnings.

Can you try this code into you localhost? May be you are executing this code directly in some html file. You should run it using some server like apache etc.

OK to use fetch instead of XHR?

not work for getting image from s3 amazon aws