在对象文字函数中更改var

Question

Hi guys I am writing some code using the object literal pattern, I have function that returns a value:

'currentLocation': function() {
    var cL = 0;
    return cL;
    },

I then need to update the variable 'cL' from another function like this:

teamStatus.currentLocation() = teamStatus.currentLocation() + teamStatus.scrollDistance();

This part is part of another function - however I get an error back stating: invalid assignment left-hand side

I am guessing I can not update the variable in this way, could anyone suggest a better method or point me in the right direction.

Any help would be greatly appreciated.

Going to add more code to highlight what I am trying to do:

'currentLocation': function() {
    var cL = 0;
    return cL;
    },
'increaseTable': function() {
    if (teamStatus.currentLocation() <= teamStatus.teamStatusTableHeight() ) {
        teamStatus.currentLocation = teamStatus.currentLocation() + teamStatus.scrollDistance();
        $("#tableTrackActual").animate({scrollTop: (teamStatus.currentLocation)});
        $("#tableMembers").animate({scrollTop: (teamStatus.currentLocation) });
        //console.log(teamStatus.currentLocation());
        teamStatus.buttonRevealer();
    }
}

As you can see increaseTable should update the value of currentLocation - help this sheds more light on what I am trying to achieve.

Answer 1

You're writing teamStatus.currentLocation() = , which calls the function teamStatus.currentLocation and tries to assign to the return value. That isn't valid. You want just teamStatus.currentLocation = — no function call.

Answer 2

The variable inside your function is completely private to that function (and any functions defined within it). If you need to create a number of functions that share a set of private variables, you can do that with a closure. For instance:

var Thing = (function() {
    var thingWideData;

    function getData() {
        return thingWideData;
    }

    function setData(newData) {
        thingWideData = newData;
    }

    return {
        getData: getData,
        setData: setData
    };

})();

What that does is create a Thing object which has getData and setData functions available for it, which get and set the completely private thingWideData variable contained by the anonymous closure. More about this pattern here and here , although the latter of those is more about private methods than private data.

Answer 3

What your code produces is:

0 = 0 + <some number>

Which variable do you want to update? cL ? You are declaring it in the function, you cannot assign a value to it from outside. Depending on the rest of your code, you might be better off with getters and setters :

var object = {
    _cL = 0,
    get currentLocation() {
        return this._cL;
    },
    set currentLocation(value) {
        this._cL = value;
    }
}

then you can do:

teamStatus.currentLocation = teamStatus.currentLocation + teamStatus.scrollDistance();

Update:

Regarding IE: If currentLocation should actually be just a number, it might be sufficient to just declare it as property:

var obj = {
    currentLocation: 0
}