JSFiddle - React, Tailwind, and code Playground

JavaScript

function getMeta(url, callback) {
    var img = new Image();
    img.src = url;
    img.onload = function() {
        callback(this.width, this.height);
    }
}

// "http://snook.ca/files/mootools_83_snookca.png" //1024x678
// "http://shijitht.files.wordpress.com/2010/08/github.png" //128x128
function alertDimensions(width, height) {
    alert(width + ' width ' + height + ' height');
}

getMeta("http://snook.ca/files/mootools_83_snookca.png", alertDimensions);