JavaScript

JavaScript arrays come with powerful built-in methods that make it easy to add, remove, find, sort, and manipulate array elements.

These methods make working with data much faster and easier.

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✅ 1. push() – Add to End

Adds an element to the end of an array.

let fruits = ["Apple", "Banana"];
fruits.push("Mango");

console.log(fruits); // ["Apple", "Banana", "Mango"]

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✅ 2. pop() – Remove from End

Removes the last element from an array.

fruits.pop();
console.log(fruits); // ["Apple", "Banana"]

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✅ 3. shift() – Remove from Start

Removes the first element from an array.

fruits.shift();
console.log(fruits); // ["Banana"]

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✅ 4. unshift() – Add to Start

Adds an element to the beginning of an array.

fruits.unshift("Orange");
console.log(fruits); // ["Orange", "Banana"]

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✅ 5. concat() – Merge Arrays

Combines two or more arrays into one new array.

let arr1 = [1, 2];
let arr2 = [3, 4];
let combined = arr1.concat(arr2);

console.log(combined); // [1, 2, 3, 4]

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✅ 6. join() – Convert Array to String

Returns a string by joining all elements with a separator.

let colors = ["Red", "Green", "Blue"];
console.log(colors.join(", ")); // "Red, Green, Blue"

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✅ 7. slice() – Extract a Portion

Returns a part of the array (without changing the original array).

let items = ["a", "b", "c", "d"];
let sliced = items.slice(1, 3);

console.log(sliced); // ["b", "c"]

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✅ 8. splice() – Add or Remove Items

Changes the contents of the array by removing/replacing elements.

let nums = [1, 2, 3, 4];
nums.splice(2, 1, 99); // From index 2, remove 1, add 99

console.log(nums); // [1, 2, 99, 4]

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✅ 9. indexOf() – Find Index

Finds the first index of a value.

let fruits = ["Apple", "Banana", "Mango"];
console.log(fruits.indexOf("Banana")); // 1

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✅ 10. includes() – Check if Exists

Checks if an item is present in the array.

console.log(fruits.includes("Mango")); // true

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✅ 11. reverse() – Reverse Order

Reverses the order of elements in the array.

let arr = [1, 2, 3];
arr.reverse();

console.log(arr); // [3, 2, 1]

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✅ 12. sort() – Sort Alphabetically or Numerically

let names = ["John", "Adam", "Zara"];
names.sort();
console.log(names); // ["Adam", "John", "Zara"]

let numbers = [30, 4, 100];
numbers.sort((a, b) => a - b);
console.log(numbers); // [4, 30, 100]

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✅ 13. forEach() – Loop Over Elements

Runs a function for each item in the array.

let nums = [10, 20, 30];
nums.forEach(function(num) {
  console.log(num);
});

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✅ 14. map() – Transform Each Item

Returns a new array after modifying each item.

let nums = [1, 2, 3];
let doubled = nums.map(num => num * 2);

console.log(doubled); // [2, 4, 6]

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✅ 15. filter() – Filter Items

Returns a new array with items that match a condition.

let nums = [5, 12, 8, 130, 44];
let result = nums.filter(num => num > 10);

console.log(result); // [12, 130, 44]

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✅ 16. reduce() – Reduce to Single Value

Applies a function to reduce the array to a single value.

let nums = [1, 2, 3, 4];
let sum = nums.reduce((total, current) => total + current);

console.log(sum); // 10

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🧠 Summary Table

Method	Description
push()	Add to end
pop()	Remove from end
shift()	Remove from start
unshift()	Add to start
concat()	Merge arrays
join()	Join elements to string
slice()	Extract part of array
splice()	Add/Remove items
indexOf()	Find index of item
includes()	Check if item exists
reverse()	Reverse array
sort()	Sort array
forEach()	Loop through elements
map()	Modify and return new array
filter()	Filter items based on condition
reduce()	Reduce array to a single value

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