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up vote 86 down vote favorite
19

Is it possible to convert an array into a function argument sequence? Example:

run({ "render": [ 10, 20, 200, 200 ] });

function run(calls) {
  var app = .... // app is retrieved from storage
  for (func in calls) {
    // What should happen in the next line?
    var args = ....(calls[func]);
    app[func](args);  // This is equivalent to app.render(10, 20, 200, 200);
  }
}
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Check for a similar question also here: stackoverflow.com/questions/2856059/… –  Wilt Feb 25 '14 at 11:14

4 Answers 4

up vote 97 down vote accepted

Yes. You'll want to use the .apply() method. For example:

app[func].apply(this||window,args);

EDIT - Actually, my ||window bit is superfluous, since this resolves to window when called outside of a function anyway.

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window does not seem to be necessary. –  JBCP Sep 24 '14 at 21:52
up vote 20 down vote 
app[func].apply(this, args);
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up vote 12 down vote

You might want to take a look at a similar question posted on Stack Overflow. It uses the .apply() method to accomplish this.

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up vote 28 down vote

A very readable example from another post on similar topic:

var x = [ 'p0', 'p1', 'p2' ];

function call_me (param0, param1, param2 ) {
    // ...
}

// Calling the function using the array with apply()
call_me.apply(this, x);

And here a link to the original post that I personally liked for it's readability

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This is not a good SO overflow answer because the details aren't included in the answer, but the link is a good one, and the linked to answer is easy to understand. –  JBCP Sep 24 '14 at 21:52
    
@JBCP I added the content to my answer. –  Wilt Sep 26 '14 at 6:58
1  
Thanks, much better! –  JBCP Sep 27 '14 at 20:28
    
If that works, why won't this work? document.body.setAttribute.apply( this, ["foo", "bar"] ); I need to send variable arguments to various object methods with different argument requirements. Quick edit: Apparently this has to be document.body, or whatever the parent is –  bryc Feb 25 at 6:17

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