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$.ajax({
    method: 'GET',
    url: 'data/bird.json',
    dataType: 'json',
    success: function() { },
    error: function() { },
    progress: function(e) {
        //make sure we can compute the length
        if(e.lengthComputable) {
            //calculate the percentage loaded
            var pct = (e.loaded / e.total) * 100;

            //log percentage loaded
            console.log(pct);
        }
        //this usually happens when Content-Length isn't set
        else {
            console.warn('Content Length not reported!');
        }
    }
});

(function($, window, undefined) {
    //is onprogress supported by browser?
    var hasOnProgress = ("onprogress" in $.ajaxSettings.xhr());

    //If not supported, do nothing
    if (!hasOnProgress) {
        return;
    }
    
    //patch ajax settings to call a progress callback
    var oldXHR = $.ajaxSettings.xhr;
    $.ajaxSettings.xhr = function() {
        var xhr = oldXHR.apply(this, arguments);
        if(xhr instanceof window.XMLHttpRequest) {
            xhr.addEventListener('progress', this.progress, false);
        }
        
        if(xhr.upload) {
            xhr.upload.addEventListener('progress', this.progress, false);
        }
        
        return xhr;
    };
})(jQuery, window);