How to return object method properly

Question

I created MyObject in javascript and I need to return its method like this

var m = new MyObject();
document.onclick = m.myMethod;

But the problem is, all the m instance variables appear to be undefined, I can't access them (even though they are defined on m) and operations on them result in NaN. How do I do this properly, so instance variables stay set when method is executed?

Is it as simple as you forgetting to use the new keyword? var m = new MyObject();? — Andy
– Andy, Commented Feb 5, 2014 at 13:31
EDIT: added "new" which was not in post, but was in code, so it is not the problem. — user1687327
– user1687327, Commented Feb 5, 2014 at 13:38

epascarello · Accepted Answer · 2014-02-05 13:31:57Z

5

It is because the this scope is the html element, not the instance.

Either a closure

document.onclick = function(evt) { m.myMethod(evt); }

or bind

document.onclick = m.myMethod.bind(m);

is needed to maintain the scope you are after.

answered Feb 5, 2014 at 13:31

epascarello

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