Javascript - Shortcut Coding Technique?

[Dental Floss]

I'm pretty intermediate at Javascript and recently was editing some facebook apps and came along this bit of script that does some sort of coding shortcut (I think).

function typeahead(obj, options, option_ids, doc_location) {
...
  // Setup the events we're listening to
  this.obj.purgeEventListeners('focus')
          .addEventListener('focus', this.onfocus.bind(this))
          .addEventListener('blur', this.onblur.bind(this))
          .addEventListener('keyup', this.onkeyup.bind(this))
          .addEventListener('keydown', this.onkeydown.bind(this))
          .addEventListener('keypress', this.onkeypress.bind(this));
...
}

Does Javascript automatically know to prepend this.obj before each addEventListener? Or is something going on here?

[AutisticCuckoo]

No, you're being tricked by the indention. It's all a single statement like this,

this.x.p().a().a().a().a().a()

The purgeEventListeners() method and the addEventListener() method apparently return the object for which they are called, allowing for a chain of method calls.

[M-M-J]

A with statement comes to mind.

Not that it should be used though.

[Dental Floss]

A with statement comes to mind.

Not that it should be used though.

This is what I have heard from others as well. Man I hate javascript

As for them being all one line, I thought javascript didn't require a semicolon to be a valid statement, just a new line character. Taken from the ECMA-262.pdf that defines this crap, semicolons are added when:

1. The offending token is separated from the previous token by at least one LineTerminator.
2. The offending token is }.

Wouldn't this code fall under the classification of being separated by a lineterminator? Each one of those lines has a different code line number associated with it, meaning newlines between each addEventListener, unless some other voodoo is going on.

And looking at Mozilla's addeventlistener definition, I don't see a return value: http colon slash slash developer.mozilla.org/en/docs/DOM:element.addEventListener

[AutisticCuckoo]

Automatic semicolon insertion is complicated. In this case there is no offending token, so no semicolons will be inserted.