String to function javascript

Question

Say i am using some of the html5 data chars and i want to know what function to call when say something is completed for a certain div tag.

so my data would look like

data-callback='jsAPI.aSubset.desiredFunction'

How would i convert that callback (a string) into the function that i want to call. A simple global function such as

data-callback='_myfunction'

<script>
    function _myfunction() { alert("yes my function"); }
    $("div").click(function() {
        var fn = $(this).data("callback");
        if (typeof fn === 'function') {
            fn();
        }
    })
</script>

but how do i do it with the previous one jsAPI.aSubset.desiredFunction Thanks

GregL · Accepted Answer · 2012-01-18 23:20:59Z

4

Sounds like a great use case for the dreaded eval().

I would do something like:

var fnString = "jsAPI.aSubset.desiredFunction";
var fn = eval(fnString);
if (typeof(fn) === "function") {
    fn.apply();

answered Jan 18, 2012 at 23:20

GregL

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Comments

Niet the Dark Absol · Accepted Answer · 2012-01-18 23:11:54Z

2

Using square brackets only works if you have no . chain.

Try this instead:

var elms = fn.split(".");
var curr = window;
var nxt;
while(nxt = elms.shift()) curr = curr[nxt];
curr();

answered Jan 18, 2012 at 23:11

Niet the Dark Absol

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Comments

user1106925 · Accepted Answer · 2012-01-18 23:08:53Z

1

Use square brackets...

jsAPI.aSubset[fn]();

so...

if (typeof jsAPI.aSubset[fn] === 'function') {
    jsAPI.aSubset[fn]();
}

answered Jan 18, 2012 at 23:08

user1106925

7 Comments

ThePrimeagen Over a year ago

I said the item was a string... Your just calling the function in the string as if i can magically just know what to call.

user1106925 Over a year ago

I should clarify that all you need/want in the data-callback attribute is the actual function name desiredFunction. If you can't know the object nesting beforehand, then you'd want something like @Kolink's answer.

user1106925 Over a year ago

@Michael: Why would it be magic to know beforehand which subset will be used?

ThePrimeagen Over a year ago

yes i know. I wont know the object nesting before hand. Else i would of done the solution i provided for in my question (which is what you did).

user1106925 Over a year ago

@Michael: The solution provided in the question wouldn't work at all, because fn would be a string.

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ja_swenberg · Accepted Answer · 2014-01-27 14:31:58Z

1

You might want to just use Function("functionstring"). The Function function returns a function from a string.

answered Jan 27, 2014 at 14:31

ja_swenberg

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Comments

duri · Accepted Answer · 2012-01-18 23:08:30Z

0

Try window[fn]() if the function is defined in the global scope.

answered Jan 18, 2012 at 23:08

duri

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