detect all JS errors, using JS

Question

I know this has probably been asked before, but I can't find where:

I know you can detect JS errors using extensions in stuff, but is there any way to detect ALL errors using JavaScript and display an alert whenever there is one?

Answer 1

In the browser define the window.onerror function. In node attached to the uncaughtException event with process.on().

This should ONLY be used if your need to trap all errors, such as in a spec runner or console.log/ debugging implementation. Otherwise, you will find yourself in a world of hurt trying to track down strange behaviour. Like several have suggested, in normal day to day code a try / catch block is the proper and best way to handle errors/exceptions.

For reference in the former case, see this (about window.error in browsers) and this (about uncaughtException in node). Examples:

Browser

window.onerror = function(error) {
  // do something clever here
  alert(error); // do NOT do this for real!
};

Node.js

process.on('uncaughtException', function(error) {
  // do something clever here
  alert(error); // do NOT do this for real!
});