How do I change a JavaScript array in place? - Stack Overflow

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How do I change a JS array in place (like a Ruby "dangerous" method, e.g. with trailing !)

Example:

If I have this:

var arr = [1, 2, 3]

How can I make this:

arr === [2, 4, 6]

(assuming I have an appropriate function for doubling numbers) in one step, without making any more variables?

How do I change a JS array in place (like a Ruby "dangerous" method, e.g. with trailing !)

Example:

If I have this:

var arr = [1, 2, 3]

How can I make this:

arr === [2, 4, 6]

(assuming I have an appropriate function for doubling numbers) in one step, without making any more variables?

• javascript
• arrays

Share Improve this question Follow edited Feb 10, 2023 at 0:20 Cadoiz 1,67622 gold badges2525 silver badges3535 bronze badges asked Jan 5, 2016 at 18:46 Choylton B. HigginbottomChoylton B. Higginbottom 2,32433 gold badges2424 silver badges3636 bronze badges 0

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1 Answer 1

Sorted by: Reset to default 5

Use Array.prototype.forEach() , third parameter is this : input array

var arr = [1, 2, 3];
arr.forEach(function(el, index, array) {
  array[index] = el * 2
});
console.log(arr)

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