JavaScript Array Methods Cheat Sheet

#javascript #webdev #programming #beginners

Method	Purpose	Example Usage	Returns
`map()`	Transforms each element and returns a new array	`arr.map(x => x * 2)`	New array
`filter()`	Returns array of elements that pass the test in the callback	`arr.filter(x => x > 0)`	New array
`reduce()`	Reduces array to single value by applying a function	`arr.reduce((a, b) => a + b, 0)`	Single value
`forEach()`	Runs a function on each array element (no return)	`arr.forEach(x => console.log(x))`	undefined
`find()`	Finds the first element that passes the test	`arr.find(x => x > 10)`	Element or undefined
`findIndex()`	Finds the index of the first element passing the test	`arr.findIndex(x => x > 10)`	Index or -1
`some()`	Checks if any element passes the test	`arr.some(x => x < 0)`	true/false
`every()`	Checks if all elements pass the test	`arr.every(x => x > 0)`	true/false
`includes()`	Checks if array contains a value	`arr.includes(2)`	true/false
`indexOf()`	Finds index of value in array (-1 if not found)	`arr.indexOf(2)`	Index or -1
`push()`	Adds elements to end, returns new length	`arr.push(4)`	New length
`pop()`	Removes last element, returns removed value	`arr.pop()`	Removed element
`shift()`	Removes first element, returns removed value	`arr.shift()`	Removed element
`unshift()`	Adds elements to start, returns new length	`arr.unshift(1)`	New length
`slice()`	Returns part of array, does not modify original	`arr.slice(1, 3)`	New array
`splice()`	Changes array by adding/removing elements	`arr.splice(1, 2)`	Removed elements
`concat()`	Combines arrays, returns new array	`arr.concat([4,5])`	New array
`join()`	Joins all elements into a string	`arr.join('-')`	String
`reverse()`	Reverses array in place	`arr.reverse()`	Same array
`sort()`	Sorts array in place	`arr.sort()`	Same array
`flat()`	Flattens nested arrays	`arr.flat()`	New array
`fill()`	Fills array with static value	`arr.fill(0)`	Same array
`from()`	Creates array from array-like object	`Array.from('abc')`	New array
`isArray()`	Checks if a value is an array	`Array.isArray(arr)`	true/false

Top comments (1)

ganesh kumar • May 16

Excellent cheat sheet! It's a handy reference for both beginners and seasoned developers. For those in Coimbatore aiming to strengthen their programming skills, this Java Course in Coimbatore offers a solid foundation that complements JavaScript learning.

Visit - appincoimbatore.com/java-course-in...