Use string to call function method? [duplicate]

Question

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How to convert a string value to a variable in javascript?

In Javascript, I have an object that looks like this:

clock = function(){
    this.load = function(){
        alert("once");
    }

    this.once = function(){
        alert("load");
    }
}
var clock =  new clock();

On the page load, I call the load() function within the clock object like so

clock.load();

When the user clicks a link, however, I need to be able to run clock.once(). Calling it like this is fine, but does not fit the dynamic needs of what I'm doing.

Let's say I need to call clock.once() when the user clicks an <a> tag:

$("a").click(function(){
    var id = $(this).attr("href").match(/[a-zA-Z]+/g);
    [id].once();
}

I figured that would work, where the object that the once() function is being called from is grabbed from the string id.

When running this, however, I get the following error:

Uncaught TypeError: Object clock has no method 'once'

Manually calling once() by using clock.once() works fine.

Really haven't given enough information. Obviously you have more than one instance of "clock", and if not, why not just repeat the call with clock.once()? Why not have once accept the id argument? — Travis J
– Travis J, Commented Dec 24, 2012 at 6:27
Why the downvote? I didn't realize not knowing something was considered bad. — Charlie
– Charlie, Commented Dec 24, 2012 at 6:29
@Charlie: I think you were downvoted for how your question is formulated (it should provide more information), not for what you are asking. — Ortiga
– Ortiga, Commented Dec 24, 2012 at 6:31
@Andre Honestly I thought it was formatted fine. That's what my code looks like. There is only one instance of clock, but when a person clicks a link that has a different href attribute, it needs to run the once() function within the id object (that is the same as the href attr clicked, they are always the same). — Charlie
– Charlie, Commented Dec 24, 2012 at 6:33

jfriend00 · Accepted Answer · 2012-12-24 06:33:13Z

1

[id].once is not not going to work because you aren't referencing a particular array that you've created that contains clock objects. You would need a particular array where you had stored multiple instances of clock objects (if you had constructed the proper array).

If you had previous create an array of clock objects:

var clocks = [];
clocks.push(new clock());
clocks.push(new clock());

Then, you could index into that particular array like this assuming id was a valid index into that array:

clocks[id]

If you're really just asking how to convert a string to a number, you can do that several ways. Here are two common ways:

parseInt(id, 10)
+id

edited Dec 24, 2012 at 6:33

answered Dec 24, 2012 at 6:25

jfriend00

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2 Comments

Felix Kling Over a year ago

It's valid syntax, but .once does not exist of course.

jfriend00 Over a year ago

@FelixKling - OK, I've modified my wording, but you get the point. It isn't code that is going to work in this context.

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