// Changing an array element

1) . length {to find length}

syntax : array_name.length

ie. let arr = [1,2,3,4,5,6];

console.log(arr.length) // output :- 6

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2) . push() {to insert element at last}

syntax : array_name.push(value_to_be_added)

ie. let arr = [1,2,3,4,5,6];

arr.push(8)

console.log(arr) // output:- [1,2,3,4,5,6,8]

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3) . slice() {to insert element at last}

cant change original array

syntax : array_name.slice(from(inclusive),to(exlusive))

ie. let arr = [1,2,3,4,5,6];

console.log(arr.slice(2,4)) //output:- [3,4]

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4) . splice() { changes the contents of an array by removing or replacing existing elements and/or adding new elements in place. }

can change original array

syntax : array_name.splice(start)
             array_name.splice(start, deleteCount)
            array_name.splice(start, deleteCount, item1)
            array_name.splice(start, deleteCount, item1, item2, itemN)

ie. const months = ['Jan', 'March', 'April', 'June'];

months.splice(4, 1, 'May'); // Replaces 1 element at index 4

console.log(months); // output: ["Jan", "Feb", "March", "April", "May"]

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5) . concat() {to merge 2 arrays}

syntax : array_name.cocat(arr1,arr2)

ie. let arr1 = [1,2,3,4,5,6];

let arr2 = [1,2,3,4,5,6];

let arr3 = []

console.log(arr3.concat(arr1,arr2)) // output :- [1,2,3,4,5,6,1,2,3,4,5,6]

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6) . copyWithin() {to merge 2 arrays}

syntax :
array_name.copyWithin(target)
array_name.copyWithin(target, start)
array_name.copyWithin(target, start, end)

const array1 = ['a', 'b', 'c', 'd', 'e'];
// Copy to index 0 the element at index 3
console.log(array1.copyWithin(0, 3, 4)); // Expected output: Array ["d", "b", "c", "d", "e"]
// Copy to index 1 all elements from index 3 to the end
console.log(array1.copyWithin(1, 3)); // Expected output: Array ["d", "d", "e", "d", "e"]

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7) . includes() {check value with given address}

syntax : array.includes(values,index)

let arr1 = [1, 2, 3, 4, 5, 6, 7, 8];
console.log(arr1.includes(5, 4)); // output :- true

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8) . indexof() {to find index of give value}

syntax : array_name.indexOf(value)

ie. let arr1 = [1,2,3,4,5,6];

console.log(arr1.indexOf(6)) // output :- 5

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9) . lastindexof() {to find last occurance index of give value}

syntax : array_name.lastIndexOf(value)

ie. let arr1 = [1,2,3,4,7,3,5,7,5,6];

console.log(arr1.lastIndexOf(7)) // output :- 7

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10) . shift() {to remove first value from an array}

syntax : array_name.shift()

ie. var array = ["GFG", "Geeks", "for", "Geeks"];
console.log(array.shift()); // output :- term removed = "GFG"
console.log(array) // output:-Geeks, for, Geeks

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11) . pop() {to remove last value from an array}

syntax : array_name.shift()

ie. var array = ["GFG", "Geeks", "for", "Geeks"];
console.log(array.pop()); // output :- term removed = "Geeks"
console.log(array) // output:-GFG, Geeks, for

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12) . reverse() {to reverse an array}

syntax : array_name.reverse()

ie. var array = ["GFG", "Geeks", "for", "Geeks"];
console.log(array.reverse()); // output :- [ 'Geeks', 'for', 'Geeks', 'GFG' ]

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13) . sort() {to sort an array}

syntax : array_name.sort()

ie. var array = [5,3,2,5,7,2,4,5];
console.log(array.sort()); // output :- [2, 2, 3, 4,5, 5, 5, 7]

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14) . tostring() {to convert an array into string form}

syntax : array_name.toString()

ie. var array = [5,3,2,5,7,2,4,5];
console.log(array.toString()); // output :- 5,3,2,5,7,2,4,5

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15) . unshift() {to add value at first position}

syntax : array_name.unshift(value)

ie. var array = ["GFG", "Geeks", "for", "Geeks"];
console.log(array.unshift(5)); // output :- term added = 5
console.log(array) // output:-5,Geeks, for, Geeks

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16) . split() {converts array into string}

syntax : array_name.split()

ie. let str = "javascript";
let ar1 = str.split("");
console.log(ar1);

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17) . map() {operation applies on all values of array}

syntax : array.map(expr)

ie. let asqr = [1, 4, 9, 16];
console.log(asqr.map(Math.sqrt));

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