Global error-handling in Javascript file

Question

I have the following code:

var test = { 
  func1: function() {...},
  func2: function() {...},
  func3: function() {...}
};

Now, I want to be able to catch any exceptions that might be thrown inside of func1/2/3. Is there an elegant way to do this without having to insert a try catch in each function?

Each function makes a call to a 3rd party library, so using window.onerror just gives me a very generic Script error, which I can't really use (due to cross origin issue apparently).

The code executes within a WebBrowser control in WPF, where the browser is targeting IE10. I'm not allowed to use anything but pure javascript and jQuery.

Whenever an exception is caught I propagate it further on to the underlying viewmodel which then logs it on the server.

T.J. Crowder · Accepted Answer · 2017-04-10 09:46:39Z

1

You could build yourself a reusable wrapper:

function wrap(f) {
    return function() {
        try {
            return f.apply(this, arguments);
        }
        catch (e) {
            errorHandler(e, f);
            throw e; // Or not, but if not, what would you return?
        }
    };
}

Then either:

var test = { 
  func1: wrap(function() {...}),
  func2: wrap(function() {...}),
  func3: wrap(function() {...})
};

or

var test = { 
  func1: function() {...},
  func2: function() {...},
  func3: function() {...}
};
Object.keys(test).forEach(function(key) {
    var func = test[key];
    if (typeof func === "function") {
        test[key] = wrap(func);
    }
});

edited Apr 10, 2017 at 9:46

answered Apr 10, 2017 at 9:37

T.J. Crowder

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5 Comments

Force444 Over a year ago

It works fine but I have an additional question. What if I want to place the Object.Keys... in another javascript file in another namespace. So we have ErrorHandler.js in which we have: var Helpers = { wrapAllFunctions: function(namespace) { Object.keys(namespace).forEach(.......)}...

Force444 Over a year ago

In the above case it doesn't work by calling ErrorHandler.Helpers.wrapAllFunctions(test); Any idea why?

T.J. Crowder Over a year ago

@DSF: JavaScript doesn't have namespaces. Many people use objects as namespaces, in which case the second example above (using forEach) works just fine -- for any functions referenced by properties in the object you pass it. If they're nested deeper, of course, you'd have to handle that.

Force444 Over a year ago

So I should be able to say wrapAllFunctions(test); and it should work even though wrapAllFunctions() is in another file?

T.J. Crowder Over a year ago

@DSF: Sure. We use functions from other files all the time. In your example above, you'd have to have ErrorHandler.Helpers = Helpers; somewhere, since Helpers is a variable (which I assume isn't a global).

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