Arrays
An array is a special variable, which can hold more than one value
- array are special type of object
- typeof array "object"
- it contain ordered list of values
- keys are indexed (starts from 0..)
- Use square bracket
[]
because key is number
Creating an array
For creating an array we use square bracket "[]"
Types of array
- Empty array
let arr = []
- array of number
let number = [1,2,3,4]
- array of strings
let vehicles = ['bike','car','bus']
- Mixed array
D/w array and objectlet mix = [143,'hello',true,undefined]
- object contain a key and value pair, where we define the key but in
- arrays we dont have to define the key it is defined by javascript
Operation perform on arrays
- Accessing
- Adding
- Updating
- deleting
Accessing
To aceesing the element of an array, we use square bracket
ex-
let vehicles = ['bike','car','bus']
vehicles[0]
'bike'
vehicles[1]
'car'
Adding
To add new element to array we use push() method. ex-
let vehicles = ['bike','car','bus']
vehicles.push('truck) '
'truck'
vehicles
['bike','car','bus','truck']
Updating
To update array we use name of the array with square bracket '[]' inside bracket give the index of element want to update
let fruits = ['apple','mango','papaya']
fruit[2]='banana'
'banana'
fruits
['apple','banana','papaya']
Deleting
delete keyword and name of the array with square bracket inside bracket give the index want to delete
let fruits = ['apple','banana','papaya']
delete fruits[0]
true
fruits
[empty, 'banana', 'papaya']
Note
Every array has speacial property called length ,which give you number of element in that array.
ex-
let vehicles = ['bike','car','bus']
vehicles.length
3
Iterating Over Arrays
There are two different ways to iterate over arrays.
- for loop (more chance of error)
for..of loop (less chance of error)
for.. of loop is new edition to the javascript family that makes accessing element of the array really really easy.
ex- for..of loop
let colors = ['red','white','green']
for(let color of colors){
console.log(color);
}
Output-
red
white
green
ex- for loop
let colors = ['red','white','green']
for(let i=0; i<colors.length ; i++){
console.log(colors[i]);
}
Output-
red
white
green