XMLHttpRequest Logger

XMLHttpRequest_Logger.js

// XMLHttpRequest Logger
function headPadding(s,l,p=' '){
  let t=Array(l+1).join(p)+s.toString();
  return l>=1?t.slice(-l):'';
}

function tailPadding(s,l,p=' '){
  let t=s.toString()+Array(l+1).join(p);
  return l>=1?t.slice(0,l):'';
}

function createUniqueId(){
  let t=headPadding(new Date().getTime().toString(16),16,'0');
  let r=headPadding(Math.floor(65536*Math.random()).toString(16),4,'0');
  return t+r;
}

var orig_XHR_open=XMLHttpRequest.prototype.open;
XMLHttpRequest.prototype.open=function(method, url, async, user, password){
  if(!this.id) this.id=createUniqueId();
  this.prevReadyState=-1;
  this.url=url;
  console.log('XMLHttpRequest['+this.id+'].open('+[].slice.call(arguments).join(',')+')');
  return orig_XHR_open.apply(this, arguments);
};

var XHR_readyState_Name=['UNSENT','OPENED','HEADERS_RECEIVED','LOADING','DONE'];

XMLHttpRequest.prototype.onreadystatechangeCallback=function(){
  if(this.readyState>=2 && this.prevReadyState!=this.readyState){
    console.log('XMLHttpRequest['+this.id+'].readystate: '+XHR_readyState_Name[this.readyState]);
  }
  if(this.readyState==2){
    if(this.url!=this.responseURL)console.log('responseURL: '+this.responseURL);
    console.log('XMLHttpRequest['+this.id+'].status: '+this.status);
    console.log('XMLHttpRequest['+this.id+'].getAllResponseHeaders():');
    console.log(this.getAllResponseHeaders());
  }
  if(this.readyState==4 && this.status>=100 && this.status<600){
//    console.log('XMLHttpRequest['+this.id+'].responseType: '+this.responseType);
    if (this.responseType == 'text' || this.responseType == ''){
      console.log('XMLHttpRequest['+this.id+'].responseText: '+this.responseText);
    }
  }
  this.prevReadyState=this.readyState;
  (this.orig_onreadystatechange)();
};

var orig_XHR_send=XMLHttpRequest.prototype.send;
XMLHttpRequest.prototype.send=function(body){
//  this.setRequestHeader('Connection','close'); // THis may be refused.
//  this.overrideMimeType('image/jpeg');
  console.log('XMLHttpRequest['+this.id+'].send('+[].slice.call(arguments).join(',')+')');
  this.orig_onreadystatechange = this.onreadystatechange;
  this.onreadystatechange = this.onreadystatechangeCallback;

  return orig_XHR_send.apply(this, arguments);
};

var orig_XHR_abort=XMLHttpRequest.prototype.abort;
XMLHttpRequest.prototype.abort=function(){
  console.log('XMLHttpRequest['+this.id+'].abort()');
  return orig_XHR_abort.apply(this);
};

var orig_XHR_setRequestHeader=XMLHttpRequest.prototype.setRequestHeader;
XMLHttpRequest.prototype.setRequestHeader=function(header,value){
  console.log('XMLHttpRequest['+this.id+'].setRequestHeader('+[].slice.call(arguments).join(',')+')');
  return orig_XHR_setRequestHeader.apply(this,arguments);
};

var orig_XHR_overrideMimeType=XMLHttpRequest.prototype.overrideMimeType;
XMLHttpRequest.prototype.overrideMimeType=function(mimeType){
  console.log('XMLHttpRequest['+this.id+'].overrideMimeType('+[].slice.call(arguments).join(',')+')');
  return orig_XHR_overrideMimeType.apply(this,arguments);
};


// Test code
xhr=new XMLHttpRequest();
xhr.open('POST',location.href);
xhr.onreadystatechange=function(){console.log('readystatechanged')};
xhr.send('abc=123&xyz=999');