In JavaScript, arrays are a special type of object that can hold multiple values in a single variable. Here are some common methods to create and manipulate arrays:
Creating an array:
let myArray = [];
Array() constructor: let myArray = new Array();
let myArray = [1, 2, 3];
Accessing elements:
let firstElement = myArray[0];
myArray[1] = 'new value';
Array properties and methods:
length: returns the number of elements in the array.push(): adds one or more elements to the end of the array.pop(): removes the last element from the array and returns it.shift(): removes the first element from the array and returns it.slice(): returns a new array containing a portion of the original array.concat(): concatenates two or more arrays and returns a new array.Looping through an array:
Using a for loop:
for(let i = 0; i < myArray.length; i++) {
console.log(myArray[i]);
}
Using a forEach loop:
myArray.forEach(function(element) {
console.log(element);
});
Array manipulation methods:
map(): creates a new array by applying a function to each element of the original array.filter(): creates a new array with only the elements that pass a certain condition.reduce(): applies a function to reduce the array to a single value.Here's an example that demonstrates some of these concepts:
let myArray = [1, 2, 3, 4, 5];
console.log(myArray.length); // Output: 5
myArray.push(6); // Adds a new element at the end
console.log(myArray); // Output: [1, 2, 3, 4, 5, 6]
let removedElement = myArray.pop(); // Removes the last element
console.log(removedElement); // Output: 6
console.log(myArray); // Output: [1, 2, 3, 4, 5]
let slicedArray = myArray.slice(1, 4); // Returns [2, 3, 4]
console.log(slicedArray);
let multipliedArray = myArray.map(function(element) {
return element * 2;
});
console.log(multipliedArray); // Output: [2, 4, 6, 8, 10]
These are just a few examples of how to create and manipulate arrays in JavaScript. There are many more methods available depending on your specific needs.