JavaScript arrays are a powerful and flexible data structure that allows developers to store and manipulate collections of values. In this blog, we will explore 15 commonly used array methods in JavaScript, including their syntax, parameters, and examples.
- concat(): This method is used to combine two or more arrays into a new array. The original arrays are not modified. For example:
let arr1 = [1, 2, 3];
let arr2 = [4, 5, 6];
let arr3 = arr1.concat(arr2);
console.log(arr3); // [1, 2, 3, 4, 5, 6]
- join(): This method is used to join all elements of an array into a string. The elements are separated by a specified separator. For example:
let arr = ["apple", "banana", "orange"];
let joined = arr.join(", ");
console.log(joined); // "apple, banana, orange"
- pop(): This method is used to remove the last element from an array and return that element. For example:
let arr = [1, 2, 3];
let popped = arr.pop();
console.log(popped); // 3
console.log(arr); // [1, 2]
- push(): This method is used to add one or more elements to the end of an array and return the new length of the array. For example:
let arr = [1, 2, 3];
let length = arr.push(4, 5);
console.log(length); // 5
console.log(arr); // [1, 2, 3, 4, 5]
- shift(): This method is used to remove the first element from an array and return that element. For example:
let arr = [1, 2, 3];
let shifted = arr.shift();
console.log(shifted); // 1
console.log(arr); // [2, 3]
- unshift(): This method is used to add one or more elements to the beginning of an array and return the new length of the array. For example:
let arr = [1, 2, 3];
let length = arr.unshift(0, -1);
console.log(length); // 5
console.log(arr); // [0, -1, 1, 2, 3]
- slice(): This method is used to extract a section of an array and return a new array. The original array is not modified. For example:
let arr = [1, 2, 3, 4, 5];
let sliced = arr.slice(1, 4);
console.log(sliced); // [2, 3, 4]
console.log(arr); // [1, 2, 3, 4, 5]
- splice(): This method is used to add or remove elements from an array at a specific index. The original array is modified. For example:
let arr = [1, 2, 3, 4, 5];
arr.splice(2, 1); // remove one element at index 2
console.log(arr); // [1, 2, 4, 5]
arr.splice(2, 0, 3); // add one element at index 2
console.log(arr); // [1, 2, 3, 4, 5]
- reverse(): This method is used to reverse the order of the elements in an array. The original array is modified. For example:
let arr = [1, 2, 3];
arr.reverse();
console.log(arr); // [3, 2, 1]
- sort(): This method is used to sort the elements in an array. The original array is modified. By default, the sort() method sorts elements as strings. To sort numbers, you need to provide a compare function. For example:
let arr = [3, 1, 4, 1, 5, 9, 2, 6, 5];
arr.sort(); // sorts as strings: ["1", "1", "2", "3", "4", "5", "5", "6", "9"]
console.log(arr);
arr.sort((a, b) => a - b); // sorts as numbers: [1, 1, 2, 3, 4, 5, 5, 6, 9]
console.log(arr);
- map(): This method is used to create a new array with the results of calling a function on every element in an array. The original array is not modified. For example:
let arr = [1, 2, 3];
let mapped = arr.map(x => x * 2);
console.log(mapped); // [2, 4, 6]
console.log(arr); // [1, 2, 3]
- filter(): This method is used to create a new array with all elements that pass a test implemented by a function. The original array is not modified. For example:
let arr = [1, 2, 3, 4, 5];
let filtered = arr.filter(x => x % 2 === 0);
console.log(filtered); // [2, 4]
console.log(arr); // [1, 2, 3, 4, 5]
- reduce(): This method is used to apply a function to each element in an array and reduce the array to a single value. The result of each iteration is passed as the first argument to the next iteration. For example:
let arr = [1, 2, 3, 4, 5];
let sum = arr.reduce((acc, cur) => acc + cur, 0);
console.log(sum); // 15
- every(): This method is used to check if all elements in an array pass a test implemented by a function. It returns true if all elements pass the test; otherwise, it returns false. For example:
let arr = [2, 4, 6, 8];
let allEven = arr.every(x => x % 2 === 0);
console.log(allEven); // true
- some(): This method is used to check if at least one element in an array passes a test implemented by a function. It returns true if at least one element passes the test; otherwise, it returns false. For example:
let arr = [1, 3, 5, 7, 9];
let hasEven = arr.some(x => x % 2 === 0);
console.log(hasEven); // false
