CODEWITHSUNDEEP
javascript
Julian Young
Julian Young

Reputation: 912

Accessing a variable by reference in Javascript

I'm trying to pass a reference to a variable and then update the contents in javascript, is that possible? For example a simple (fail) example would be...

var globalVar = 2;

function storeThis ( target, value ) {
    eval(target) = value;
}

storeThis( 'globalVar', 5);
alert('globalVar now equals ' + globalVar);

This of course doesn't work, can anyone help?

Upvotes: 5

Views: 305

Answers (3)

scraze
scraze

Reputation: 21

If you really want to use eval, you could use the following:

var globalVar = 2;

function storeThis( target, value ) {
    eval( target + ' = ' + value );
}

storeThis( 'globalVar', 5 );
alert('globalVar now equals ' + globalVar);

Upvotes: 2

jasongetsdown
jasongetsdown

Reputation: 1305

In this case the code in storeThis already has access to globalVar so there's no need to pass it in.

Your sample is identical to:

var globalVar = 2;

function storeThis(value) {
    globalVar = value;
}

storeThis(5);

What exactly are you trying to do?

Scalars can't be passed by reference in javascript. If you need to do that either use the Number type or create your own object like:

var myObj = { foo: 2 };

Upvotes: 3

tcooc
tcooc

Reputation: 21249

Eval does not return a value.

This will work:

window[target] = value;

(however, you are not passing the reference, you're passing the variable name)

Upvotes: 4

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