Passing functions in javascript

Question

With reference to the code from here

With reference to the addListener(instance:Object, eventName:string, handler:Function) function. Here we pass in a handler. So toggleBounce is called when you click it.

I could also change it to var toggleFn = function toggleBounce() {....) and pass in toggleFn

My question is, can I pass in a function which takes parameters, for example if I wanted the handler to be a zoom(mapOptions.zoom -5) or similar function.

I know this is essentially a 'how do you pass functions as parameters' question but I just can't get it to work with different combinations.

function initialize() {
  var mapOptions = {zoom: 13, center: stockholm };
  map = new google.maps.Map(document.getElementById("map_canvas"), mapOptions);

  marker = new google.maps.Marker({map:map,position: parliament });
  google.maps.event.addListener(marker, 'click', toggleBounce);
}

function toggleBounce() {
  if (marker.getAnimation() != null) { marker.setAnimation(null);} 
  else {marker.setAnimation(google.maps.Animation.BOUNCE);}
}

JCOC611 · Accepted Answer · 2011-03-06 19:31:05Z

3

You can pass a anonymous function:

functionToPassTo(function(){ zoom(mapOptions.zoom -5) });

You can also pass variables:

var options = "something";
functionToPassTo(function(){ zoom(options) });

The only other way would be to store the function in a variable:

var options = "something",
func=function(){ zoom(options) });
functionToPassTo(func);

edited Mar 6, 2011 at 19:31

answered Mar 6, 2011 at 17:03

JCOC611

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7 Comments

Tim Over a year ago

Cheers. Is this the only way to do it? Can I not pass in a reference?

Pointy Over a year ago

@Tim you can pass a function reference, but that just gets you to the function itself and doesn't handle your parameters. What you want is a reference to a function that calls the function you really want to call, passing the parameters too.

Tim Over a year ago

Ok but say I wanted to pass in a local variable, such as the mapOptions as one of the parameters? The toggleBounce() method still can't access it

Tim Over a year ago

@JCOC611 thank you for that. I can get what I want to do using anonymous functions now. However, I'd still like to know if its possible any other way. I personally hate the mess of anonymous functions bring to code but if its the only way to do this so be it.

JCOC611 Over a year ago

@Tim: Edited again, you can store the new function in a variable...although that really is just wasting more code...

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