How to empty an array in JavaScript

The simple way to empty an array in JavaScript is through assigning 0 to the property length of the array affected. For Example

let numbers = [1,3,5,7,9];

numbers.length = 0;

console.log(numbers);
// []

This is possible because the length property is read/write property in an array. Therefore, you can assign zero and the array will be clear.

Comments

[Brian Todd]

Wouldnt it be the same assigning to an empty array?
let numbers = [] ;

[Jon Randy 🎖️]

Nope. If you had another reference to the original array, the original array would still remain at the other reference - you have done nothing to the original array.

Compare:

let numbers = [1, 3, 5, 7, 9];
let numbers_b = numbers; // another reference to same array
numbers.length = 0;

console.log(numbers_b);
// []

And:

let numbers = [1, 3, 5, 7, 9];
let numbers_b = numbers; // another reference to same array
numbers = [];

console.log(numbers_b);
// [1, 3, 5, 7, 9]

Assigning to an empty array does exactly that - assigns a new array to the variable. Entirely different to emptying an existing array. 'Emptying' an array by simply overwriting it with a new empty array could easily cause unexpected problems.

[JacKyDev]

I think Not..
Its the Same result but the author used the existing Array in context and you create an complete new Array for context

[Tobias Nickel]

yes, any just by doing so, the author introduce a implicit dependencies between components. Using the same array all over the and somewhere it get emptied will cause some nice side effects.

This will give you some fun debugging session.