Use the Array.prototype.push method to append values to the end of an array:
// initialize array
var arr = [
"Hi",
"Hello",
"Bonjour"
];
// append new value to the array
arr.push("Hola");
console.log(arr);You can use the push() function to append more than one value to an array in a single call:
// initialize array
var arr = ["Hi", "Hello", "Bonjour", "Hola"];
// append multiple values to the array
arr.push("Salut", "Hey");
// display all values
for (var i = 0; i < arr.length; i++) {
console.log(arr[i]);
}Note that the push() method returns the updated length of the array.
Update
If you want to add the items of one array to another array, you can use firstArray.concat(secondArray):
var arr = [
"apple",
"banana",
"cherry"
];
// Do not forget to assign the result as, unlike push, concat does not change the existing array
arr = arr.concat([
"dragonfruit",
"elderberry",
"fig"
]);
console.log(arr);Update
Just an addition to this answer if you want to prepend any value to the start of an array (i.e. first index) then you can use Array.prototype.unshift for this purpose.
var arr = [1, 2, 3];
arr.unshift(0);
console.log(arr);It also supports appending multiple values at once just like push.
Update
Another way with ES6 syntax is to return a new array with the spread syntax. This leaves the original array unchanged, but returns a new array with new items appended or prepended, compliant with the spirit of functional programming.
const arr1 = [
"Hi",
"Hello",
"Bonjour",
];
const arr2 = [
"Ciao",
"Hej",
"Merhaba",
];
const newArr1 = [
...arr1,
"Salut",
];
const newArr2 = [
"Salut",
...arr2,
];
const newArr3 = [
...arr1,
...arr2,
];
console.log(newArr1, newArr2, newArr3);Can you only add an array to another array?
In ES5 Javascript, how do I add an item to an array and return the new array immediately, without using concat? - Stack Overflow
How can I add an element to an array?
Three ways to append an item to an array (Mutative)
Use the Array.prototype.push method to append values to the end of an array:
// initialize array
var arr = [
"Hi",
"Hello",
"Bonjour"
];
// append new value to the array
arr.push("Hola");
console.log(arr);You can use the push() function to append more than one value to an array in a single call:
// initialize array
var arr = ["Hi", "Hello", "Bonjour", "Hola"];
// append multiple values to the array
arr.push("Salut", "Hey");
// display all values
for (var i = 0; i < arr.length; i++) {
console.log(arr[i]);
}Note that the push() method returns the updated length of the array.
Update
If you want to add the items of one array to another array, you can use firstArray.concat(secondArray):
var arr = [
"apple",
"banana",
"cherry"
];
// Do not forget to assign the result as, unlike push, concat does not change the existing array
arr = arr.concat([
"dragonfruit",
"elderberry",
"fig"
]);
console.log(arr);Update
Just an addition to this answer if you want to prepend any value to the start of an array (i.e. first index) then you can use Array.prototype.unshift for this purpose.
var arr = [1, 2, 3];
arr.unshift(0);
console.log(arr);It also supports appending multiple values at once just like push.
Update
Another way with ES6 syntax is to return a new array with the spread syntax. This leaves the original array unchanged, but returns a new array with new items appended or prepended, compliant with the spirit of functional programming.
const arr1 = [
"Hi",
"Hello",
"Bonjour",
];
const arr2 = [
"Ciao",
"Hej",
"Merhaba",
];
const newArr1 = [
...arr1,
"Salut",
];
const newArr2 = [
"Salut",
...arr2,
];
const newArr3 = [
...arr1,
...arr2,
];
console.log(newArr1, newArr2, newArr3);If you're only appending a single variable, then push() works just fine. If you need to append another array, use concat():
var ar1 = [1, 2, 3];
var ar2 = [4, 5, 6];
var ar3 = ar1.concat(ar2);
alert(ar1);
alert(ar2);
alert(ar3);The concat does not affect ar1 and ar2 unless reassigned, for example:
var ar1 = [1, 2, 3];
var ar2 = [4, 5, 6];
ar1 = ar1.concat(ar2);
alert(ar1);There is a lot of great information on JavaScript Reference.
Hi there!
I'm new to JavaScript and was learning about arrays today and saw that the instructor only added an array to another array. Is it possible to add something that is not an array into an array? Iyes, how can I do that?
Thanks in advance!
I know the following code works
['a', 'b'].concat(['c']);But I find it ugly code (combining two arrays just to add a single item to the end of the first array).
The concat() method can be given a single (or multiple) values without the need of encapsulating the value(s) in an array first, for example:
['a', 'b'].concat('c'); // instead of .concat(['c']);
From MDN (my emphasis):
Arrays and/or values to concatenate into a new array.
Besides from that there are limited options without using extension and existing methods.
Example on how to extend the Array (this will return current array though):
Array.prototype.append = function(item) {
this.push(item);
return this
};
var a = [1, 2, 3];
console.log(a.append(4))Optionally create a simple function as @torazaburo suggests, which can take array and item as argument:
function append(arr, item) {
arr.push(item);
return arr;
}
or using concat():
function append(arr, item) {
return arr.concat(item)
}
I can offer two methods for Array.prototype.insert() which will allow you insert single or multiple elements starting from any index within the array.
1) mutates the array it's called upon and returns it
Array.prototype.insert = function(i,...rest){
this.splice(i,0,...rest)
return this
}
var a = [3,4,8,9];
console.log(JSON.stringify(a.insert(2,5,6,7)));ES5 compliant version of the above snippet.
Array.prototype.insert = function(i){
this.splice.apply(this,[i,0].concat(Array.prototype.slice.call(arguments,1)));
return this;
};
2) Not mutates the array it's called upon and returns a new one
Array.prototype.insert = function(i,...rest){
return this.slice(0,i).concat(rest,this.slice(i));
}
var a = [3,4,8,9],
b = a.insert(2,5,6,7);
console.log(JSON.stringify(a));
console.log(JSON.stringify(b));ES5 compliant version of the above snippet.
Array.prototype.insert = function(i){
return this.slice(0,i).concat(Array.prototype.slice.call(arguments,1),this.slice(i));
}