How can I store reference to a variable within an array?

Question

I\'m trying to create an array that maps strings to variables. It seems that the array stores the current value of the variable instead of storing a reference to the variabl

Answer 1

Put an object into the array instead:

var name = {};
name.title = "foo";

var array = [];

array["reference"] = name;

name.title = "bar";

// now returns "bar"
array["reference"].title;

Answer 2

My solution to saving a reference is to pass a function instead:

If the variable you want to reference is called 'myTarget', then use:

myRef = function (newVal) {
            if (newVal != undefined)
                myTarget = newVal;
            return myTarget;
        }

To read the value, use myRef();. To set the value, use myRef(value_to_set);.

Helpfully, you can also assign this to an array element as well:

var myArray = [myRef];

Then use myArray0 to read and myArray[0](value_to_set) to write.

Disclaimer: I've only tested this with a numerical target as that is my use case.

Answer 3

Try pushing an object to the array instead and altering values within it.

var ar = [];

var obj = {value: 10};
ar[ar.length] = obj;

obj.value = 12;

alert(ar[0].value);

Answer 4

My solution to saving a reference is to pass a function instead:

If the variable you want to reference is called myTarget, then use:

myRef = function (newVal) {
    if (newVal != undefined) myTarget = newVal;
    return myTarget;
}

To read the value, use myRef();. To set the value, use myRef(<the value you want to set>);.

Helpfully, you can also assign this to an array element as well:

var myArray = [myRef];

Then use myArray[0]() to read and myArray[0](<new value>) to write.

Disclaimer: I've only tested this with a numerical target as that is my use case.

Answer 5

You can't.

JavaScript always pass by value. And everything is an object; var stores the pointer, hence it's pass by pointer's value.

If your name = "bar" is supposed to be inside a function, you'll need to pass in the whole array instead. The function will then need to change it using array["reference"] = "bar".

Btw, [] is an array literal. {} is an object literal. That array["reference"] works because an Array is also an object, but array is meant to be accessed by 0-based index. You probably want to use {} instead.

And foo["bar"] is equivalent to foo.bar. The longer syntax is more useful if the key can be dynamic, e.g., foo[bar], not at all the same with foo.bar (or if you want to use a minimizer like Google's Closure Compiler).