Abstracting_XMLHttpRequests.js

function xhrGet(reqUri, callback, type) {
    var caller = xhrGet.caller;
    var xhr = new XMLHttpRequest();
    xhr.open("GET", reqUri, true);
    if (type) xhr.responseType = type;
    
    xhr.onload=function () {
      if (callback) {
        try {
          callback(xhr);
        }
        catch(e) {
          throw 'xhrGet failed:\n' + reqUri + '\nException: ' + e + '\nresponseText: ' + xhr.responseText + '\ncaller: ' + caller;
        }
      }
    };
    xhr.send();
};

parseJSON = function (xhr) {
    var parsedJSON = JSON.parse(xhr.responseText);

    var x = parsedJSON['frames']['chaingun_impact.png']['spriteSourceSize']['x'];
    console.log(x);
    return x;
};

xhrGet('weaponJSON', parseJSON, null);