JavaScript array; Through tutorial, i am going to explain you about JavaScript arrays [] with examples.
JavaScript Array
JavaScript array is a variable, which is hold different data type elements in it.
Note that:- An element data type can be numbers, strings, and objects, etc.
Define array in javaScript
See the following way to define or declare array in javaScript; as shown below:
1 – Using Array
constructor
Here, i will take an example for declare array using constructor in javaScript; as shown below:
let arr = new Array();
The arr
array is empty i.e. it holds no element.
Next, i will take an second example for array with elements; as shown below:
let arr = new Array(9,10,8,7,6);
2 – Using []
notation
To define or declare array using literal []
notation, define arrays.
See the following examples:
let arr = [element1, element2, element3];
The array literal form uses the square brackets [] to wrap a comma-separated list of elements.
See the following example, to creates num
array:
let num = [4, 3, 2];
An array with different type elements
According to javaScript array defination, an array can hold different data types of elements in it.
Here, i will take an simple example for demostration; how to declare or define array with different data types; as shown below:
var arr = ["hello", 520, "test", 960, true];
To get elements in an array
If you want to get or access elements from an array in javaScript; so you can see the following example for that; as shown below:
For example; if you have an array with elements; as shown below:
var arr = ["hello", 520, "world"];
And you want to get or access the elements of the arr
array in javascript; as shown below for how to access or get elements from an array in javaScript:
console.log(arr[0]); // 'hello' console.log(arr[1]); // 520 console.log(arr[2]); // 'world'
To Get Length of an array
To find or get the length of an array in javaScript; so you can use the length
property of it.
See the following example:
var arr = ["hello", 520, "world"]; console.log(arr.length); // 3
The javascript array length
property is writable. It’s very good benefit to you. For what?, So you can add or remove elements in an array by changing the value of the length
property.
For examples,
Change the length
property of the arr
array to 5 to add one new element with an initial value of undefined
at the end of the array.
// add 1 element var arr = ["hello", 520, "world"]; arr.length = 5; console.log(arr[3]); // undefined
Likewise, To remove elements from an array in js, define the length
property of the arr
array to 3 to remove the last two elements of the array.
Then. to access the third element of the array, it returns undefined
.
// remove the last 3 elements var arr = ["hello", 520, "world"]; arr.length = 3; console.log(arr[3]); // undefined
To check if variable an array in JavaScript
You can use the typeof operator or isArray() function to check if variable is an array or not in JavaScript.
When you can use typeof
operator method with an array in javascript, it returns object
as shown in the following example:
let arr = ['hello', 'my', 'world']; console.log(typeof arr); // object
Check if variable is array javascript, you use Array.isArray()
method.
See the following example:
console.log(Array.isArray(arr)); // true
Add and Remove Element From Array JavaScript
If you want to add the elements of beginning and end from an array and remove elements of beginning and end from an array, you can use the following methods in js:
push(...items)
addsitems
to the end.pop()
removes the element from the end and returns it.shift()
removes the element from the beginning and returns it.unshift(...items)
addsitems
to the beginning.splice
removes from a specific Array index.
Conclusion
JavaScript Array tutorial; In this tutorial, you have learned how to declare array in javascript and how to add, remove, and get elements from array in javascript.