How to Empty an Array in JavaScript

Empty an Array in JavaScript #

To empty an array, call the splice() method, passing it 0 as a parameter - splice(0). The method will empty the original array, by removing and returning all its elements starting at index zero.

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const arr = ['a', 'b', 'c'];

arr.splice(0);

console.log(arr); // 👉️ []

The parameter we passed to the Array.splice method is the start index - the index at which we start changing the array.

The second parameter the splice method takes is delete count - the number of elements that should be removed from the array, from the start index onwards.

For our purposes we provide a start index of 0 to delete all elements and empty the array.

To empty an array, reassign the variable storing the array and set it to an empty array, e.g. arr = []. Note that you can only reassign variables, declared using the let and var keywords. This is the most performant way to empty an array in JavaScript.

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let arr = ['a', 'b', 'c'];

arr = [];

console.log(arr); // 👉️ []

Notice that we use the let keyword to to declare the arr variable. Had we used the const keyword, we wouldn't be able to reassign the variable and set it to an empty array.

An alternative approach is to set the array's length to 0.

To empty an array, set its length property to 0. When the length property of an array is changed, every element which has an index that is not smaller than the new length of the array gets automatically deleted.

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const arr = ['a', 'b', 'c'];

arr.length = 0;

console.log(arr); // 👉️ []

By setting the array's length to 0, we automatically delete all elements from the array with an index that is not smaller than 0, which covers the entire array.

Further Reading #

• Find the Odd Numbers in an Array using JavaScript
• Find the Even numbers in an Array using JavaScript
• Get a random Element from an Array using JavaScript
• Get Multiple Random Elements from an Array in JavaScript
• Add Array of Values to an Existing Set in JavaScript
• Create a Map from an Array using JavaScript
• Check if a Value is NOT in an Array using JavaScript
• How to Flatten an Array using JavaScript
• Convert an Array to JSON using JavaScript
• Create an Object from Two Arrays in JavaScript
• Convert an Object to an Array of Objects in JavaScript
• Convert an Array of Objects to a Map in JavaScript