bad low level API call

[boussou]

(Not a big deal)
on vue/src/directives/on.js:

reset function should be :
reset: function () {
var el = this.iframeBind
? this.el.contentWindow
: this.el
this.handler && el.removeEventListener(this.arg, this.handler)
},

Added code is "this.handler && "
Reason: at init, call to removeEventListener() while this.handler is null
according to specs, calls must always have the handler
https://developer.mozilla.org/en-US/docs/Web/API/EventTarget.removeEventListener

This happens because in update() function " this.reset() " (line 4253) is called before this.handler (line 4256) is defined.

[yyx990803]

Thanks, it's usually fine to call it with a null or undefined listener value, since the spec says:

Calling removeEventListener with arguments which do not identify any currently registered EventListener on the EventTarget has no effect.

But in this case checking for handler first does avoid an expensive removeEventListener call so this is still a good change.

[boussou]

Good. I am monitoring the event bindings so it is useful to me.