How to use the Javascript Array Clear method?

How do you clear an array in JavaScript?

Short answer: set its length to zero with arr.length = 0. It empties the array itself, works with const and every variable that points to that array sees it empty. If you only need a fresh empty array in one variable, arr = [] also works, but the old array keeps its items.

const fruits = ["apple", "banana", "cherry"];
fruits.length = 0;
console.log(fruits);   // []

There is no built-in clear() method for arrays. Set and Map have one, arrays don't.

length = 0 empties the array everywhere, = [] only gives one variable a new array, and a const can't be reassigned.

Every way to clear an array

For most code, arr.length = 0 is the clearest choice. Use splice(0) when you also want the items you removed.

Clear an array with length = 0

An array's length can be written. Setting it to 0 removes every item, and setting it to a smaller number keeps only the first ones:

const nums = [1, 2, 3, 4, 5];
 
nums.length = 2;
console.log(nums);   // [1, 2]
 
nums.length = 0;
console.log(nums);   // []

Because it changes the array itself, it also empties arrays inside objects, like cart.items.length = 0.

Clear an array with splice()

splice(0) removes every item from position 0 and returns them in a new array. Use it when you want to empty the array and keep what was in it:

const queue = ["task1", "task2", "task3"];
const done = queue.splice(0);
 
console.log(queue);   // []
console.log(done);    // ["task1", "task2", "task3"]

splice(2) removes everything from position 2 onwards, so [1, 2, 3, 4, 5].splice(2) leaves [1, 2].

arr = []: a new array, not an empty one

Assigning [] doesn't empty the array. It makes the variable point to a new empty array. Any other variable, function or object that had the old array still sees its items:

let current = [1, 2, 3];
const saved = current;
 
current = [];
console.log(current);   // []
console.log(saved);     // [1, 2, 3]

Compare it with length = 0:

const current = [1, 2, 3];
const saved = current;
 
current.length = 0;
console.log(saved);     // []

arr = [] is fine when nothing else uses the old array, for example a local variable you are about to fill again. It needs let: with const you get TypeError: Assignment to constant variable.

Clear an array in React and other state

In React state, don't change the array in place. Set a new empty array instead, so React sees the change:

const [items, setItems] = useState(["a", "b"]);
 
setItems([]);   // correct
// items.length = 0;   // the screen doesn't update

The same applies to Vue's ref([]) with list.value = [], and to any store that compares references to detect changes.

Check that an array is empty

const arr = [];
 
if (arr.length === 0) {
  console.log("empty");
}
 
Array.isArray(arr) && arr.length === 0;   // true

Don't compare with arr === []: that is always false, because it compares two different arrays.

Use AI to clear arrays the right way

An assistant like ChatGPT, Claude or GitHub Copilot can tell you which method fits your code and why an array isn't emptying. These three prompts are ready to copy.

1. Choose a method

In my JavaScript code I need to empty this array: [paste your code].
Other parts of the code use it like this: [explain or paste].
Which method should I use and why?

2. Explain a bug

I clear an array in JavaScript with [your code], but [what happens] and I expected
[what you expected]. Explain why and how to fix it.

3. Clear state in a framework

I use [React / Vue / Angular] and I want to empty this list in my state: [paste the code].
Show me the correct way so the screen updates.

Test the answer with console.log() on every variable that points to the array.

Common problems when clearing an array

Related guides

• JavaScript array fill()
• JavaScript array slice()
• How to clone an array in JavaScript
• How to get the last element of an array in JavaScript
• JavaScript array intersection
• JavaScript array some()