How to disable a function temporarily in JavaScript?

Question

I am trying to disable a function in JavaScript so that it only can be called once every 300ms.

To do this, I guessed the best approach would be to do sth like this:

var locked = (function () {
    var lock = null;
    return function () {
        if (lock != null)
            return false;

        lock = setTimeout(function () {
            lock = null;
        }, 300);
        return true;
    };
})();

And use this lock in other functions like this:

function superImportantFunction() {
    if(locked()) return;
}

Now, this does not work for some reason. Do you have any better suggestions or maybe a reason why the code does not work?

Thanks!

Community · Accepted Answer · 2020-06-20 09:12:55Z

2

how does it not work? Seems to work for me. Although you probably need to create separate locks for different functions unless you want them to share the lock. And you need to reverse your return values.

edit reversing the boolean

var lockF = function () {
    var lock = null;
    return function () {
        if (lock != null)
            return true;

        lock = setTimeout(function () {
            lock = null;
        }, 300);
        return false;
    };
}; 
var func1locked = lockF();

var func2locked = lockF();

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Sep 10, 2010 at 14:22

einarmagnus

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Comments

JoshNaro · Accepted Answer · 2010-09-10 15:04:47Z

0

In

var lock = null;
return function () {
    if (lock != null)
        return false;

you are setting lock to null and then checking if lock is not equal to null. That is, your return function will always return false.

Try moving your lock declaration out of the Locked() function:

var lock = null;
var locked = (function () {    
return function () {
    if (lock != null)
        return false;

    lock = setTimeout(function () {
        lock = null;
    }, 300);
    return true;
};
})();

answered Sep 10, 2010 at 15:04

JoshNaro

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1 Comment

einarmagnus Over a year ago

no, that is plain wrong. if it is null it is not != null.

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How to disable a function temporarily in JavaScript?

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edit reversing the boolean

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