JavaScript Array
An array is a special variable, which can hold more than one value:
1. Creating an Array
const arr = [232,"Array", false, true];
console.log(arr);
output:
[ 232, 'Array', false, true ]
2. Spaces and line breaks are not important. A declaration can span multiple lines
const cars = ["Audi","Mercedes",
"Lamborghini","Jugar","BMW",
"This is an Array",8787,9789
];
console.log(cars);
output:
[
'Audi',
'Mercedes',
'Lamborghini',
'Jugar',
'BMW',
'This is an Array',
8787,
9789
]
3. You can also create an array, and then provide the elements:
const arr =[];
arr[0] = "Arrays";
arr[1] = "Strings";
arr[2] = 'This is an array element';
console.log(arr);
output:
[ 'Arrays', 'Strings', 'This is an array element' ]
const arr =[];
arr[0] = "Arrays";
arr[1] = "Strings";
arr[2] = 'This is an array element';
arr[0] = "Javaascript";
console.log(arr);
console.log(arr[0]);
console.log(arr[1]);
output:
[ 'Javaascript', 'Strings', 'This is an array element' ]
Javaascript
Strings
4. The following example also creates an Array, and assigns values to it.
const cars = new Array("Saab","Tesla", "BMW");
console.log(cars);
output:
[ 'Saab', 'Tesla', 'BMW' ]
5. Accessing Array Elements
const arrr = ["element","Method","Binary","Trees", "prototype","work hard"];
console.log(arrr);
console.log(arrr[3])
console.log(arrr[0][1]);
console.log(arrr[4]);
output:
[ 'element', 'Method', 'Binary', 'Trees', 'prototype', 'work hard' ]
Trees
l
prototype
6. Changing an Array Element
let arrEle = ["Paris","Hong kong","Moscow","Tokyo","New york"];
console.log(arrEle);
arrEle[0] = "Japan"; // changing an array element 0 index.
console.log(arrEle);
output:
[ 'Paris', 'Hong kong', 'Moscow', 'Tokyo', 'New york' ]
[ 'Japan', 'Hong kong', 'Moscow', 'Tokyo', 'New york' ]
N.B Arrays are Objects
7. Array sort()
let arrEle = ["Paris","Hong kong","Moscow","Tokyo","New york"];
console.log(arrEle.sort());
output:
[ 'Hong kong', 'Moscow', 'New york', 'Paris', 'Tokyo' ]
let arrEle = [454,5445,"Paris","Hong kong","Moscow","Tokyo","New york",true,false];
console.log(arrEle.sort());
output:
[
454, 5445,
'Hong kong', 'Moscow',
'New york', 'Paris',
'Tokyo', false,
true
]
Accessing the First Array Element
const varr = [
"Hello there", "Planet",
"Galaxy", "Universe",
010101, true,"Die Hard"
];
console.log(varr[0]);
output:
Hello there
Accessing the Last Array Element
const arr = [
"Hello there", "Planet",
"Galaxy", "Universe",
010101, true,"Die Hard"
];
console.log(arr[arr.length -1]);
output:
Die Hard
8. Adding Array Elements.
The easiest way to add a new element to an array is using the push() method.
const city = ["Mumbai","Chennai","Delhi","Pune"];
console.log(city);
city.push("Bengalore");
console.log(city);
output:
[ 'Mumbai', 'Chennai', 'Delhi', 'Pune' ]
[ 'Mumbai', 'Chennai', 'Delhi', 'Pune', 'Bengalore' ]
New element can also be added to an array using the length property.
const city = ["Mumbai","Chennai","Delhi","Pune"];
console.log(city);
city[city.length] = "Heyderabad";
console.log(city);
output:
[ 'Mumbai', 'Chennai', 'Delhi', 'Pune' ]
[ 'Mumbai', 'Chennai', 'Delhi', 'Pune', 'Heyderabad' ]
Note:
Many programming languages support arrays with named indexes.
Arrays with named indexes are called associative arrays (or hashes).
JavaScript does not support arrays with named indexes.
In JavaScript, arrays always use numbered indexes.
9. javaScript code for concat() method
function func1(){
let num1 = [11,12,13];
let num2 = [14,15,16];
let num3 = [17, 18, 19];
console.log(num1.concat(num2,num3)) ;
}
func1();
output:
[
11, 12, 13, 14, 15,
16, 17, 18, 19
]
const num1 = [11,12,13];
num2 = [14,15,16];
num3 = [17,18,19];
console.log(num1.concat(num2,num3));
output:
[
11, 12, 13, 14, 15,
16, 17, 18, 19
]
var alpha = ['a','b','c'];
console.log(alpha.concat(1,[2,3]));
output:
[ 'a', 'b', 'c', 1, 2, 3 ]
let num1 = [[23]];
let num2 = [89, [67]];
console.log(num1.concat(num2));
output:
[ [ 23 ], 89, [ 67 ] ]
function fun(){
let alpha = ["a","b","c"];
console.log(alpha.concat(1,[2,3]));
}
fun();
output:
[ 'a', 'b', 'c', 1, 2, 3 ]
let alpha = ["a", "b","c"];
console.log(alpha.concat(1,[2,3]));
output:
[ 'a', 'b', 'c', 1, 2, 3 ]
10. JavaScript Array copyWithin() Method
const array = [1,2,3,4,5,6,7];
console.log(array.copyWithin(0,3,6)); // copyWithin(Target,start,end)
output:
[
4, 5, 6, 4,
5, 6, 7
]
const arr = [1,2,3,4,5,6,7];
console.log(arr.copyWithin(0,4)); // output: 5,6,7,4,5,6,7
output:
[
5, 6, 7, 4,
5, 6, 7
]
11. Array fill() Method
function fun(){
let arr = [1,23,46,58];
// fill array with 87
arr.fill(99);
console.log(arr);
}
fun();
output:
[ 99, 99, 99, 99 ]
function fun(){
let arr = [1,23,46,58];
// fill array with 87
arr.fill("Die Hard");
console.log(arr);
}
fun();
output:
[ 'Die Hard', 'Die Hard', 'Die Hard', 'Die Hard' ]
arr.fill(value, start, end)
Parameters: This method accepts three parameters as mentioned above and described below:
let arr = [1,23,46,58];
arr.fill(100, 1,3); // fill(value, start, end)
console.log(arr);
output:
[ 1, 100, 100, 58 ]
let arr = ["move","system","run",true];
arr.fill("Now",2);
console.log(arr);
output:
[ 'move', 'system', 'Now', 'Now' ]
function myarr(){
let arr = [1,3,4,58];
arr.fill(87,1,3); // fill(value,start,end)
console.log(arr);
}
myarr();
[ 1, 87, 87, 58 ]
12. JavaScript Array filter() Method
function canVolte(age){
return age >= 18;
}
function fun1(){
let filtered = [24,33,16,40].filter(canVolte)
console.log(filtered);
}
fun1();
output:
[ 24, 33, 40 ]
function isPositive(value){
return value > 0;
}
let filtered = [11,1,0,-1,899,-1,-5,232].filter(isPositive);
console.log(filtered);
output:
[ 11, 1, 899, 232 ]
function isEven(value){
return value % 2 ===0;
}
let fil = [11,22,23,45,33,123,68,58,54,89].filter(isEven);
console.log(fil);
output:
[ 22, 68, 58, 54 ]
function isEv(value){
return value % 2 ===0;
}
function resl(){
let arr = [23,56,41,25,38,25,80].filter(isEv);
console.log(arr);
}
resl();
output:
[ 56, 38, 80 ]
13. JavaScript Array find() Method
var arr = [-10,-0.20,0.30,-40,-50,5];
var found = arr.find(function (element){
return element > 0;
});
console.log(found);
output: 0.3
let arr = [20,30,40,50,60];
let findd = arr.find(function (lan){
return lan > 40;
})
console.log(findd);
const arr = [2,4,7,8,9];
const total = arr.find(function (arr){
return arr > 4;
})
console.log(total);
output: 7
14. JavaScript Array findIndex() Method
findIndex() method to find the index of positive number from an array.
positive element at index 3. So it print 3.
let arr = [-10, -0.30,-40,0.20,-736]
let fin = arr.findIndex(function (arr){
return arr > 0;
})
console.log(fin);
output: 3
function isOdd(element, index, array){
return (element % 2 ==1);
}
console.log([4,7,8,12].findIndex(isOdd));
output: 1
The arr.findIndex() method used to return the index of
the first element in a given array that satisfies the provided testing
function. Otherwise, -1 is returned.
function isOdd(element, index, array){
return (element % 2 ==1);
}
console.log([4,6,8,12].findIndex(isOdd));
output: -1
let array = [10,20,30,110,70];
function index_element(element){
return element > 25;
}
console.log(array.findIndex(index_element));
output: 2
function isPrime(n){
if(n === 1){
return false;
}
else if(n === 2){
return true;
}
else{
for(let x = 2; x < n; x++){
if(n % x === 0){
return false;
}
}
return true;
}
}
console.log([4,6,8,12].findIndex(isPrime));
console.log([4,6,7,12,18].findIndex(isPrime));
output:
-1
2
15. JavaScript Array flat() Method
The arr.flat() method was introduced in ES2019. It is used to flatten an array, to reduce the nesting of an array.
The flat() method is heavily used in functional programming paradigm of JavaScript. Before flat() method was introduced in JavaScript, various libraries such as underscore.js were primarily used.
const numbers = [["1","2"], ["3","4",["5",["6"],"7"]]];
const flatNumbers = numbers.flat(Infinity);
console.log(flatNumbers);
output:
[
'1', '2', '3',
'4', '5', '6',
'7'
]
let nestedArray = [1,[2,3],[[]],[4, [5]],6];
let zeroFlat = nestedArray.flat(0);
console.log(`Zero level flattened array: ${zeroFlat}`);
let oneFlat = nestedArray.flat(1);
console.log(`One level flattened array: ${oneFlat}`);
let twoFlat = nestedArray.flat(2);
console.log(`Two level flattened array: ${twoFlat}`);
let threeFlat = nestedArray.flat(3);
console.log(`Three levels flattened array: ${threeFlat}`);
output:
Zero level flattened array: 1,2,3,,4,5,6
One level flattened array: 1,2,3,,4,5,6
Two level flattened array: 1,2,3,4,5,6
Three levels flattened array: 1,2,3,4,5,6
let arr = [1,2,3,,4]
let newArr = arr.flat();
console.log(newArr);
output:
[ 1, 2, 3, 4 ]
16. JavaScript | array .flatMap()
17. JavaScript Array forEach() Method
function func(){
const items = [12,24,36];
const copy = [];
items.forEach(function (item){
copy.push(item + item +2);
})
console.log(copy);
}
func();
output:
[ 26, 50, 74 ]
const items = [1,29,47];
const copy = [];
items.forEach(function(item){
copy.push(item * item)
});
console.log(copy);
output:
[ 1, 841, 2209 ]
18. JavaScript | Array from() Method
19. JavaScript Array includes() Method
The array.includes() method is used to know either a
particular element is present in the array or not and accordingly, it
returns true or false i.e, if the element is present, then it returns
true otherwise false.
let name = ["gfg", "cse", "geeks","portal"];
let a = name.includes('gfg');
console.log(a);
output: true
let arr = [1,2,3,4,5];
let aa = arr.includes(2);
console.log(aa);
let arr = [1,2,3,4,5].includes(2);
console.log(arr);
let arr = [1,2,3,4,5].includes(7);
console.log(arr);
20. JavaScript Array indexOf() Method
The arr.indexOf() method is used to find the index of the first occurrence of the search element provided as the argument to the method.
array.indexOf(element, start)This method accepts two parameters as mentioned above.
let arr = ['somebody', 'told', 'you', 'how', 'much', 'i care','you'];
let fin = arr.indexOf("how");
console.log(fin);
output: 3
const arr2 = [1,2,3,4,5,6].indexOf(4);
console.log(arr2);
output: 3
In this example the method will searched for the element 9 in that array if not found then return -1.
const num = [1,2,3,4,5,6,7].indexOf(9);
console.log(num);
output: -1
21. JavaScript Array isArray() Method
The arr.isArray() method determines whether the value
passed to this function is an array or not. This function returns true
if the argument passed is array else it returns false.
function func(){
console.log(Array.isArray('football'));
}
func();
output: false
function func(){
console.log(Array.isArray(['football']));
};
func();
output: true
function f2(){
console.log(Array.isArray({name: "Lin"}))
};
f2();
output: false
22. JavaScript Array join() Method
The arr.join() method is used to join the elements of
an array into a string. The elements of the string will be separated by a
specified separator and its default value is a comma(, ).
function func(){
let a = [1,2,3,4,5,6];
console.log(a.join(" | "));
}
func();
output:
1 | 2 | 3 | 4 | 5 | 6
function func(){
let a = [1,2,3,4,5,6];
console.log(a.join(" waw "));
}
func();
output:
1 waw 2 waw 3 waw 4 waw 5 waw 6
function fun(){
let a = [1,2,3,4,5,6,7];
console.log(a.join(''));
}
fun();
output:
1234567
23. JavaScript Array keys() Method
The array.keys() method is used to return a new array iterator which contains the keys for each index in the given input array.
let a = [5,6,7];
let iterator = a.keys();
for(let key of iterator){
console.log(key + ' ');
};
0
1
2
const arr = ["Learning","JavaScript","Array","GeeksForGeeks","OK"];
let iterator = arr.keys();
for(let key of iterator){
console.log(key);
}
output:
0
1
2
3
4
24. JavaScript Array lastIndexOf() Method
The arr.lastIndexOf() method is used to find the index of the last occurrence of the search element provided as the argument to the function.
let language = ["python","Java","C++","C#","JS","GO","Ruby","swift"];
let tat = language.lastIndexOf("C#");
console.log(tat);
let language = ["python","Java","C++","C#","JS","GO","Ruby","swift"];
let tat = language.lastIndexOf("python");
console.log(tat);
output: 0
let num = [1,2,3,4,5,6].lastIndexOf(3);
console.log(num);
output: 2
let num = [1,2,3,4,5,6].lastIndexOf(8);
console.log(num);
output: -1
let language = ["python","Java","C++","C#","JS","GO","Ruby","swift"];
let tat = language.lastIndexOf("R");
console.log(tat);
output: -1
25. JavaScript Array map() Method
The arr.map() method creates a new array with the
results of a called function for every array element. This function
calls the argument function once for each element of the given array in
order.
function fun(){
let arr = [14,10,11,00];
let newArr = arr.map(Math.sqrt);
console.log(newArr);
}
fun();
output:
[ 3.7416573867739413, 3.1622776601683795, 3.3166247903554, 0 ]
let arr = [2,56,78,34,65];
let newArr = arr.map(function(num){
return num / 2;
})
console.log(newArr);
output:
[ 1, 28, 39, 17, 32.5 ]
const arr = [10, 64,121,23];
const newArr = arr.map(Math.sqrt);
console.log(newArr);
[ 3.1622776601683795, 8, 11, 4.795831523312719 ]
function fun(){
let arr = [2,56,78,34,65];
let newArrr = arr.map(function (num){
return num/2;
})
console.log(newArrr);
}
fun();
output:
[ 1, 28, 39, 17, 32.5 ]
function funnn(){
let arr = [10,64,121,23];
let newArr = arr.map(Math.sqrt);
console.log(newArr);
}
funnn();
output:
[ 3.1622776601683795, 8, 11, 4.795831523312719 ]
26. JavaScript Array.of() function]
Whenever we need to get elements of an array that time we take the help of the Array.of( ) method in JavaScript.
console.log(Array.of(11,21,33));
console.log(Array.of(0,0,0));
console.log(Array.of(["Kismat","Amy","Shakeel", "Minto"]));
console.log(Array.of(1,2,3,"Japan"));
output:
[ 11, 21, 33 ]
[ 0, 0, 0 ]
[ [ 'Kismat', 'Amy', 'Shakeel', 'Minto' ] ]
[ 1, 2, 3, 'Japan' ]
27. JavaScript Array pop() Method
The arr.pop() method is used to remove the last element
of the array and also returns the removed element. This function
decreases the length of the array by 1.
function popp(){
let arr = ["Pop","function","JavaScript","Code"];
let newArr = arr.pop();
console.log(newArr);
}
popp();
output:
Code
let num = [12,33,44,345,3212];
let pp = num.pop();
console.log(num);
console.log(pp);
output:
[ 12, 33, 44, 345 ]
3212
let num = [12,33,44,345,3212];
num.pop();
console.log(num);
output:
[ 12, 33, 44, 345 ]
function fun(){
let arr = [23,234,567,3];
let popped = arr.pop();
console.log(popped);
console.log(arr);
}
fun();
output:
3
[ 23, 234, 567 ]
function arr(){
let arr = [];
let new_arr = arr.pop();
console.log(new_arr);
}
arr();
28. JavaScript Array push() Method
The arr.push() method is used to push one or more
values into the array. This method changes the length of the array by
the number of elements added to the array.
function pushh(){
let arr = ["Lebanon", "Hongkong","Japan","Tokyo"];
let arr1 = arr.push("New York");
console.log(arr);
}
pushh();
output:
[ 'Lebanon', 'Hongkong', 'Japan', 'Tokyo', 'New York' ]
function fu(){
let arr = [323,43,354];
console.log(arr.push('Coder','Programmer','Developer'));
console.log(arr);
}
fu();
output:
6
[ 323, 43, 354, 'Coder', 'Programmer', 'Developer' ]
29. JavaScript Array reduce() Method
The arr.reduce() method in JavaScript is used to reduce
the array to a single value and executes a provided function for each
value of the array (from left-to-right) and the return value of the
function is stored in an accumulator.
var arr = [10,20,30,40,50,60];
function sumOfArray(sum, num){
return sum + num;
}
function func(item){
console.log(arr.reduce(sumOfArray));
}
func();
output: 210
let arr = [1.5,20.3,11.1,40.7];
function sumOfArray(sum, num){
return sum + Math.round(num);
}
function funn(item){
console.log(arr.reduce(sumOfArray,0));
}
funn();
output: 74
30. JavaScript Array reduceRight() Method
The arr.reduceRight() method in JavaScript is used to convert elements of the given array from right to left to a single value.
const num = [175,50,25];
function subOfArray(total,num){
return total - num;
}
function result(item){
console.log(num.reduceRight(subOfArray));
}
result();
output: -200
let arr = [10,20,30,40,50,60];
function subArray(total,num){
return total - num;
}
function fun1(item){
console.log(arr.reduceRight(subArray));
}
fun1();
output: -90
31. JavaScript Array reverse() Method
The arr.reverse() method is used for in-place reversal of the array. The first element of the array becomes the last element and vice versa.
const arr = [34,234,567,4];
console.log(arr);
const new_arr = arr.reverse();
console.log(new_arr);
output:
[ 34, 234, 567, 4 ]
[ 4, 567, 234, 34 ]
function func(){
let arr =['Portal','Science','Computer','Coder'];
console.log(arr)
let new_arr = arr.reverse();
console.log(new_arr);
}
func();
output:
[ 'Portal', 'Science', 'Computer', 'Coder' ]
[ 'Coder', 'Computer', 'Science', 'Portal' ]
32. JavaScript Array shift() Method
The arr.shift() method removes the first element of the array thus reducing the size of the original array by 1.
function funNam(){
let arr = ["London","Turkey","Abu Dhabi","Brunui"];
let value = arr.shift();
console.log(value);
console.log(arr);
}
funNam();
output:
London
[ 'Turkey', 'Abu Dhabi', 'Brunui' ]
function func(){
let arrr = [34,234,567,4];
let value = arrr.shift();
console.log(value);
console.log(arrr);
}
func();
output:
34
[ 234, 567, 4 ]
function funcc(){
let array = [];
let nwArray = array.shift();
console.log(nwArray);
}
funcc();
output:
undefined
33. JavaScript Array slice() Method
The arr.slice() method returns a new array containing a portion of the array on which it is implemented. The original remains unchanged.
function func(){
let arr = [23,56,87,32,75,13];
let new_arr = arr.slice(2,4);
console.log(arr);
console.log(new_arr);
}
func();
output:
[ 23, 56, 87, 32, 75, 13 ]
[ 87, 32 ]
let arr = [23,56,87,32,75,13];
let new_arr = arr.slice(2);
console.log(arr);
console.log(new_arr);
output:
[ 23, 56, 87, 32, 75, 13 ]
[ 87, 32, 75, 13 ]
let arr = [23,56,87,32,75,13];
let new_arr = arr.slice();
console.log(arr);
console.log(new_arr);
output:
[ 23, 56, 87, 32, 75, 13 ]
[ 23, 56, 87, 32, 75, 13 ]
34. JavaScript Array some() Method
The arr.some() method checks whether at least one of the elements of the array satisfies the condition checked by the argument method.
function checkAvailabity(arr,val){
return arr.some(function (arrVal) {
return val === arrVal;
})
}
function func(){
let arr = [2,5,8,1,4]
console.log(checkAvailabity(arr,2));
console.log(checkAvailabity(arr,87))
}
func();
output:
true
false
let arr = [2,5,8,1,4];
function checkAvailability(arr,val){
return arr.some(function(arrVal){
return val === arrVal;
})
}
console.log(checkAvailability(arr,2));
console.log(checkAvailability(arr,87));
output:
true
false
function isGreterThan5(element, index,array){
return element > 5;
}
function func(){
let arr = [2,4,8,1,4];
let value = arr.some(isGreterThan5)
console.log(value);
}
func();
output:
true
function isGreterThan5(element,index,array){
return element > 5;
}
function func(){
let array = [-2,5,3,1,4];
let value = array.some(isGreterThan5)
console.log(value)
}
func();
35. JavaScript Array sort() Method
The arr.sort() method is used to sort the array in place in a given order according to the compare() function. If the method is omitted then the array is sorted in ascending order.
function func(){
let arr = ["Geeks","for","Coder"];
console.log(arr);
console.log(arr.sort());
}
func();
output:
[ 'Geeks', 'for', 'Coder' ]
[ 'Coder', 'Geeks', 'for' ]
const arr = [2,5,7,1,4];
console.log(arr);
console.log(arr.sort());
output:
[ 2, 5, 7, 1, 4 ]
[ 1, 2, 4, 5, 7 ]
const arr = [2,5,8,1,4];
console.log(arr.sort(function (a,b){
return a + b * 2;
}));
console.log(arr);
output:
[ 2, 5, 8, 1, 4 ]
[ 2, 5, 8, 1, 4 ]
function func(){
let arr = [2,5,8,1,4];
console.log(arr.sort());
console.log(arr);
};
func();
output:
[ 1, 2, 4, 5, 8 ]
[ 1, 2, 4, 5, 8 ]
function func() {
// Original array
var arr = [2, 5, 8, 1, 4];
console.log(arr.sort(function(a, b) {
return a + 2 * b;
}));
console.log(arr);
}
func();
output:
[ 2, 5, 8, 1, 4 ]
[ 2, 5, 8, 1, 4 ]
36. JavaScript Array splice() Method
The arr.splice() method is an inbuilt method in
JavaScript which is used to modify the contents of an array by removing
the existing elements and/or by adding new elements.
var webDvlop = ["HTML", "CSS", "JS", "Bootstrap"];
console.log(webDvlop);
// Add 'React_Native' and 'Php' after removing 'JS'.
var removed = webDvlop.splice(2, 1, 'PHP', 'React_Native')
// No Removing only Insertion from 2nd
// index from the ending
webDvlop.splice(-2, 0, 'React');
output:
[ 'HTML', 'CSS', 'JS', 'Bootstrap' ]
var languages = ['C++', 'Java', 'Html', 'Python', 'C'];
console.log(languages);
// Add 'Julia' and 'Php' after removing 'Html'.
var removed = languages.splice(2, 1, 'Julia', 'Php')
// No Removing only Insertion from 2nd index from the ending
languages.splice(-2, 0, 'Pascal')
console.log(languages)
output:
[ 'C++', 'Java', 'Html', 'Python', 'C' ]
[
'C++', 'Java',
'Julia', 'Php',
'Pascal', 'Python',
'C'
]
37. JavaScript | array .toLocaleString() function
The array.toLocaleString() is an inbuilt function in JavaScript which is basically used to convert the element of the given array to string.
var name = "geeksforgeeks";
var number = 567;
// It will give current date and time.
var date = new Date();
// Here A is an array containing elements of above variables.
var A = [ name, number, date ];
// applying array.toLocaleString function.
var string = A.toLocaleString();
// printing string.
console.log(string);
output:
geeksforgeeks,567,4/9/2022, 10:55:25 PM
var name = [ "Ram", "Sheeta", "Geeta" ];
var number1 = 3.45;
var number2 = [ 23, 34, 54 ];
// Here A is an array containing elements of above variables.
var A = [ name, number1, number2 ];
// applying array.toLocaleString function.
var string = A.toLocaleString();
// printing string.
console.log(string);
output:
Ram,Sheeta,Geeta,3.45,23,34,54
38. JavaScript Array toString() Method
The arr.toString() method returns the string representation of the array elements.
function func() {
// Original array
var arr = ["Geeks", "for", "Geeks"];
// Creating a string
var str = arr.toString();
console.log(str);
}
func();
output:
Geeks,for,Geeks
function func() {
// Original array
var arr = [2, 5, 8, 1, 4];
// Creating a string
var str = arr.toString();
console.log(str);
}
func();
output:
2,5,8,1,4
39. JavaScript Array unshift() Method
The arr.unshift() method is used to add one or more
elements to the beginning of the given array. This function increases
the length of the existing array by the number of elements added to the
array.
function func() {
// Original array
var array = ["GFG", "Geeks", "for", "Geeks"];
// Checking for condition in array
var value = array.unshift("GeeksforGeeks");
console.log(value);
console.log(array);
}
func();
output:
5
[ 'GeeksforGeeks', 'GFG', 'Geeks', 'for',
var arr = [23,76,19,94];
console.log(arr.unshift());
console.log(arr);
output:
4
[ 23, 76, 19, 94 ]
function sayHello() {
var arr = [23,76,19,94];
// Adding elements to the front of the array
console.log(arr.unshift(28,65));
console.log(arr);
}
sayHello();
output:
6
[ 28, 65, 23, 76, 19, 94 ]
function sayHello() {
var arr = [23,76,19,94];
// Adding elements to the front of the array
console.log(arr.unshift(28,65));
console.log(arr);
}
sayHello();
output:
6
[ 28, 65, 23, 76, 19, 94 ]