Get all javascript errors on page/javascript error handling

Question

I want to be able to send myself all the javascript errors on a page. I am an extension developer, so the following has an emphasis on making sure the dom is ready before making calls to it.

I investigated adding some functionality to the throw to also send or mail the exceptions, but I didn't find this to be possible.

1:main solution to this, a window.onerror handler:

window.onerror = function(e, url, line){   mailError('onerror: ' + e + ' URL:' + url + ' Line:' + line);   console.error('\nLine ' + line + ':');   setTimeout(function(){retry();}, 100); //mainly useful in content scripts for extensions,    return true;  } 

May also need to do same thing via jQuery:

$(window).error(    function(e, url, line){     //handle error   } ); 

The downfall of this is that your code has stopped executing.

To avoid errors stopping execution, it's best to use callbacks to make sure code executes in a certain sequence, and to utilize events wherever possible. You can also protect dom calls with a few techniques

$(document).ready({   //you usually won't get bad dom calls wrapping your code in this }); 

You can also consider running code on window.onload

window.onload = function(){   //you page will probably twitch upon executing code at this time   //but you will almost never have a bad dom call }; 

Another technique

if (document.getElementById('iNeedThisElement')) {   //doin work!   document.getElementById('iNeedThisElement').style.display = 'block'; } else {   var stillNeedToTakeCareOfX = true; //false otherwise since it's undefined   mailError('iNeedThisElement was unavailable...'); } 

Using these techniques and just debugging your application, you should be fairly well off. Since console.error, .warn, and .log statements cannot be retrieved and reported back to your, a small alternative suite is provided below:

var Xe = { }; //Extreme error suite  function extraInfo(e){    //e optional    if(!e)e = true;     //add an extra debug info, such as navigator or current URL    return ' currentURL: '+ document.URL +          '\n userAgent: ' + navigator.userAgent +          '\n platform: '  + navigator.platform +          '\n userid: '    + localStorage.userid +          '\n language: '  + navigator.langauge +          '\n cookies?: '  + navigator.cookiesEnabled; }  Xe.error = function(e){   console.error(e); //maintain original functionality   mailError('Xe err: ' + e + extraInfo() ); }   Xe.warn = function(e){   console.warn(e);   mailError('Xe warn: ' + e + extraInfo() ); }   Xe.log = function(e){   console.log(e);   mailError('Xe log: ' + e + extraInfo() ); } 

As a last ditch, you can continually attempt to execute a chunk of code until it executes without errors. This is "2" below.

2:group code in large chunks and attempting to re-execute x seconds later after catching an error, or continue to next chunk of code

//defExe = DEFinitely EXEcute this code   //functionArg, reference to a function holding a large chunk of code   //seconds, timeout in milliseconds to re-attempt error free execution of this function function defExe(functionArg, seconds) {   //seconds is optional   if (!seconds)seconds = 300;    try {     functionArg();   } catch(e) {     //mail the error plus extra info     mailError('caught ' + e + ' attempting to re-execute ' + functionArg.name + ' in ' + seconds + ' milliseconds');      //re-attempt to execute this code     setTimeout(function(){         defExe(functionArg, seconds);      }, seconds);   } } 

this it is then used like

//array to group function chunks var fn = [ ];  fn[1] = function (){   //a large chunk of javascript } defExe(fn[1]);  fn[2] = function(){   //another chunk of your program } defExe(fn[2]); 

#2 Summary: Group code in functions and run in try-catch block, repeating if an errors are caught

Answer 1

I have mine working with window.onerror and it doesn't stop my javascript:

window.onerror = function(error, url, line) {     controller.sendLog({acc:'error', data:'ERR:'+error+' URL:'+url+' L:'+line}); }; 

Note that controller.sendLog is a function that sends this data to a logging php.

Can be because you're causing some javascript error inside that function?