// scripts/error.js
functionerror() {
var foo = {};
return foo.bar();
}

// tests/scripts/errorTest.js
it('throws a TypeError', function () {
  should.throws(error, TypeError);
});

// scripts/badHandler.js
functionbadHandler(fn) {
try {
return fn();
  } catch (e) { }
returnnull;
}

// tests/scripts/badHandlerTest.js
it('returns a value without errors', function() {
var fn = function() {
return1;
  };
var result = badHandler(fn);
  result.should.equal(1);
});
it('returns a null with errors', function() {
var fn = function() {
thrownewError('random error');
  };
var result = badHandler(fn);
  should(result).equal(null);
});

// scripts/badHandlerDom.js
(function (handler, bomb) {
var badButton = document.getElementById('bad');
if (badButton) {
    badButton.addEventListener('click', function () {
      handler(bomb);
console.log('Imagine, getting promoted for hiding mistakes');
    });
  }
}(badHandler, error));

// scripts/uglyHandler.js
functionuglyHandler(fn) {
try {
return fn();
  } catch (e) {
thrownewError('a new error');
  }
}

// scripts/specifiedError.js
// Create a custom error
var SpecifiedError = functionSpecifiedError(message) {
this.name = 'SpecifiedError';
this.message = message || '';
this.stack = (newError()).stack;
};
SpecifiedError.prototype = newError();
SpecifiedError.prototype.constructor = SpecifiedError;
// scripts/uglyHandlerImproved.js
functionuglyHandlerImproved(fn) {
try {
return fn();
  } catch (e) {
thrownew SpecifiedError(e.message);
  }
}
// tests/scripts/uglyHandlerImprovedTest.js
it('returns a specified error with errors', function () {
var fn = function () {
thrownewTypeError('type error');
  };
  should.throws(function () {
    uglyHandlerImproved(fn);
  }, SpecifiedError);
});

functionmain(bomb) {
try {
    bomb();
  } catch (e) {
// Handle all the error things
  }
}

// scripts/errorHandlerDom.js
window.addEventListener('error', function (e) {
var error = e.error;
console.log(error);
});

// scripts/errorAjaxHandlerDom.js
window.addEventListener('error', function (e) {
var stack = e.error.stack;
var message = e.error.toString();
if (stack) {
    message += '\n' + stack;
  }
var xhr = new XMLHttpRequest();
  xhr.open('POST', '/log', true);
// Fire an Ajax request with error details
  xhr.send(message);
});

// scripts/asyncHandler.js
functionasyncHandler(fn) {
try {
// This rips the potential bomb from the current context
    setTimeout(function () {
      fn();
    }, 1);
  } catch (e) { }
}

setTimeout(function () {
try {
    fn();
  } catch (e) {
// Handle this async error
  }
}, 1);