Optional arguments javascript trick

Question

I'm trying to do the following:

eventService.emit = function(name, optionalArg1, optionalArg2,... ){
    $rootScope.$broadcast(name, optionalArg1, optionalArg2,...);
};

with an unlimited number of optional arguments. (broadcast "definition": $broadcast(string, args...))

I thought

eventService.emit =$rootScope.$broadcast;

would work but it doesn't($broadcast function may access to $rootscope attributes) and

eventService.emit = function(){
    $rootScope.$broadcast(arguments);
};

doesn't seem to work

Thanks for the help

original code:

services.factory('eventService', function($rootScope, $http){
    var eventObject = {};

    eventObject.emit = function(name){

       $rootScope.$broadcast(name);

    };
    return eventObject;
});

you can use the typeof operator to see if a variable is defined — starbeamrainbowlabs
– starbeamrainbowlabs, Commented Aug 9, 2012 at 19:54
eventService.emit = function(){ $rootScope.$broadcast(Array.prototype.slice.call(arguments)); }; doesn't seem to work, the event thrown by $broadcast is never catched — cricardol
– cricardol, Commented Aug 9, 2012 at 20:18

cricardol · Accepted Answer · 2012-08-09 21:12:46Z

6

You could try

eventService.emit = function(){

    $rootScope.$broadcast.apply($rootScope, arguments); //you can change "this" to whatever you need
};

Here you are executing $rootScope.$broadcast with the parameters in the arguments "array" (it's not really an array but behaves like one), and using this (the parameter) as this in the function.

edited Aug 9, 2012 at 21:12

cricardol

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answered Aug 9, 2012 at 19:54

nicosantangelo

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3 Comments

Jason Orendorff Over a year ago

It is probably better to pass $rootScope instead of this. That's more like what the question is asking for - though it may or may not matter in practice.

nicosantangelo Over a year ago

Yes it's probably right, I really didn't know what would suit the situation better, hence the comment :).

cricardol Over a year ago

Is is working with the $rootscope instead of 'this'...thx guys

Wolfgang Stengel · Accepted Answer · 2012-08-09 20:12:39Z

1

You could use apply() (documentation here):

eventService.emit = function(name, optionalArg1, optionalArg2,... )
{
    $rootScope.$broadcast.apply(this, arguments);
};

[1]:

edited Aug 9, 2012 at 20:12

answered Aug 9, 2012 at 20:07

Wolfgang Stengel

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2 Comments

cricardol Over a year ago

what is the purpose of the first argument??

cricardol Over a year ago

it seems like a valid solution (when I look at the doc) but I can't make it work....i also tried with the function: 'call': developer.mozilla.org/en-US/docs/JavaScript/Reference/…

Travis J · Accepted Answer · 2012-08-09 19:54:42Z

0

What I do when I want a lot of options is this:

function myFunction(options){
 if( options["whateverOptionYouWant"] != undefined ){
  //TODO: implement whatever option you want
 }
 if( options["whateverOTHEROptionYouWant"] != undefined ){
  //TODO: implement whatever OTHER option you want
 }
}

and so on for as many options as I need.

Call it like this:

myFunction({ whateverOptionYouWant: "some option variable" });
myFunction();
myFunction({ 
 whateverOptionYouWant: "some option variable", 
 whateverOTHEROptionYouWant: "some other variable"});

answered Aug 9, 2012 at 19:54

Travis J

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1 Comment

cricardol Over a year ago

it is not really the solution I expected, I would like to use the "arguments" object which is "A king of" array (javascriptweblog.wordpress.com/2011/01/18/…)

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