Rewrite array from the function. Using argument reference

Question

Can you please explain how to worship JavaScript gods and work around this one.

var array = ['old'];
    
function manageArray(targetArray) {
  targetArray = ['new'];
}

manageArray(array);
alert(array);

The reason for this is to create a pattern that will have filter logic and instead of declaring explicit methods for each array have one universal to rule over all.

Desired logic

var numbers = ['1', '2']
var words = ['room', 'car']
var color = ['red', 'blue']

function manageArray(targetArray, value) {
  targetArray = targetArray.filter(existingValue, () => {
    return existingValue != value
  })
}

manageArray(words, 'car');
alert(words);

What are you expecting to happen here? `targetArray` is scoped to your function — StudioTime, May 13 '17 at 12:52

score 1 · Answer 1 · answered May 13 '17 at 12:57

1

You'll be able to access the array if you have your function return it:

var array = ['old'];
    
function manageArray(targetArray) {
  targetArray = ['new'];
  return targetArray
}

array = manageArray(array);
alert(array);

answered May 13 '17 at 12:57

jeremye

1,368
9
19

score 1 · Accepted Answer · edited May 23 '17 at 12:10

From what I understand, you want to pass your variable by reference. It is sad that Javascript pass array as value. There are a few ugly workaround.

var array = {v: ['old'] };

function manageArray(targetArray) {
  targetArray.v = ['new'];
}

manageArray(array);

or

var array = ['old'];

function manageArray(targetArray) {
    return ['new'];
}

array = manageArray(array);

For further reading:

Pass Variables by Reference in Javascript

Rewrite array from the function. Using argument reference

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