Pushing functions into an Array in Javascript

Question

Is there a way to push a list of functions into an associative array? Here's what I'm trying to do:

var inits = {
    "first"  : fn1(),
    "second" : fn2(),
    "third"  : fn3(),
    "fourth" : fn4()

};

var functions = ['first','fourth'];

for(var index in functions ) {

    inits[functions[index]];

}

The important part here is to be able to name each function and have it called based on a given array of function names. I can do this in PHP but can't figure it out how to do it in javascript.

Keep in mind that an associative array is actually just an object in Javascript. — Kodlee Yin
– Kodlee Yin, Commented Jun 18, 2014 at 19:09
@Dimitri As pointed out in a comment in one of the answers, make sure when the "associative array" is defined, that the values of the elements are function definitions and not function calls! — Kodlee Yin
– Kodlee Yin, Commented Jun 18, 2014 at 19:11
@alexn I would chain the functions instead of storing them in an object — Mr. Alien
– Mr. Alien, Commented Jun 18, 2014 at 19:56

user229044 · Accepted Answer · 2014-06-18 19:05:55Z

2

First, you're not actually storing functions. You're storing the return value of functions.

To store the function, you'd use

var inits = {
  'first': fn1,
  'second': fn2,
   ...
};

Secondly, you're iterating incorrectly over the array.

Use forEach:

functions = ['first', 'fourth'];

functions.forEach(function (fn) {
    inits[fn];
});

Thirdly, in your loop, you don't actually try to invoke the function. If that's your intent, you're missing a ():

functions.forEach(function (fn) {
    inits[fn]();
});

answered Jun 18, 2014 at 19:05

user229044♦

241k41 gold badges346 silver badges350 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

user229044 Over a year ago

@Dimitri It's not, though you could just as easily store the functions directly: functions [fn1, fn2]. The person who told you this is "absurd" had no business doing so, there is too little context for him to have drawn such a conclusion.

svidgen · Accepted Answer · 2014-06-18 19:12:09Z

1

Just a few small changes should make it work:

var inits = {
    "first"  : function() { /* make sure there's a function body */ },

    "second" : fn2,   // or this, if you intend to call a function named `fn2`
                      // or assigned to a locally accessible fn2 variable.

    "third"  : fn3(), // or this, if fn3() returns a function ...
    "fourth" : fn4(), // but, this version *probably* isn't what you want.

};

var functions = ['first','fourth'];

// generally speaking, don't use for-in on an array.
for(var i = 0; i < functions.length; i++) {

    // use parentheses to invoke the function
    inits[functions[i]]();

}

edited Jun 18, 2014 at 19:12

answered Jun 18, 2014 at 19:07

svidgen

14.4k4 gold badges37 silver badges60 bronze badges

5 Comments

alexn Over a year ago

That will only work if fn1, fn2 etc. returns functions.

alexn Over a year ago

You probably mean function() { .. } instead of fn1() { .. }.

svidgen Over a year ago

@alexn Doesn't look like there is a downvoter ... Just someone rapidly up-voting and un-voting ...

Dimitri Over a year ago

@svidgen Thank you, just a major oversight on my part; this makes perfect sense! Why would something like this be considered bad programming?

svidgen Over a year ago

@Dimitri Not sure. I think we're missing too much context to say what you're doing is categorically absurd or bad ...

Collectives™ on Stack Overflow

Pushing functions into an Array in Javascript

2 Answers 2

1 Comment

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related