Concatenation function name in js

Question

Is there any way to concat a js function name? right now I have this:

switch (playId) {
        case "11":
            play11();
            break;
        case "22":
            play22();
            break;
        case "33":
            play33();
            break;
        case "44":
            play44();
            break;
        default:
            break;
    }

and I want to do somthing like this:

var function = "play" + playId + "()";

and call it.. what is the best way if possible?

Solution:

What I did with the help of thefourtheye and xdazz is very simple:

var playFunction = window["play" + playId];
    playFunction();

xdazz · Accepted Answer · 2014-04-24 08:27:21Z

8

If these functions are defined in global scope, then you could get them from the global object:

var foo = window["play" + taskId];

Otherwise you could put them together in an object like another answer suggested.

answered Apr 24, 2014 at 8:27

xdazz

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1 Comment

René Over a year ago

It's not limited to the global scope(but out of scope for this question) but I would always try to avoid it. It can break after minifying the code and searching for unused functions becomes impossible in larger projects. Using a 'dictionary' object is not much more work and very readable. - answer is good though.

thefourtheye · Accepted Answer · 2014-04-24 08:25:03Z

8

The best way is to put them in an object like this

var functions = {
    11: play11,
    22: play22,
    33: play33,
    44: play44
};

and then invoke it like this

functions[taksId]();

Since you don't want to fail if taskId is not found, you can do

if (functions.hasOwnProperty(taskId)) {
    functions[taksId]();
}

answered Apr 24, 2014 at 8:25

thefourtheye

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Comments

thedjaney · Accepted Answer · 2014-04-24 08:32:00Z

1

if you put the functions in an array:

var functions = {
    'play1':function(){},
    'play2':function(){}
}

Call it like this:

functions['play'+number]();

answered Apr 24, 2014 at 8:32

thedjaney

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