can.debounce keeps the context after being called the first time

[colinexl]

Hello,

We believe there is a bug in the way can.debounce works:

function (fn, time, context) {
  var timeout;
  return function () {
    var args = arguments;
    context = context || this; // buggy line, can be fixed by using var myContext = context || this
    clearTimeout(timeout);
    timeout = setTimeout(function () {
      fn.apply(context, args);
    }, time);
  };
}

The context is saved in the returned function's closure so that all future calls to the debounce will get the saved context.

We discovered this bug when using can.debounce to create a event handler function for a can.Component. Once the can.Component is destroyed and reinitialized, the old (destroyed) can.Component's context is used in the can.debounce function.

I can create a JSFiddle if required but this is pretty easy to reproduce.

Thanks,
Colin Zhu

[daffl]

Makes sense. The easiest way would probably be to change it to:

function (fn, time, context) {
  var timeout;
  return function () {
    var args = arguments;
    clearTimeout(timeout);
    timeout = setTimeout(can.proxy(function () {
      fn.apply(this, args);
    }, context || this), time);
  };
}

[colinexl]

Yep I think that will solve the issue.

[justinbmeyer]

@daffl or @colinexl anyway one of you can get a pull request / test in by tomorrow? Otherwise, we might save this fix for 2.1.1.

[ccummings]

@colinexl Can you include your use case in this thread