JavaScript Array Reference
JavaScript Array is used to store multiple elements in a single variable. It can hold various data types, including numbers, strings, objects, and even other arrays. It is often used when we want to store a list of elements and access them by a single variable.
Syntax:
const arr = ["Item1", "Item2", "Item3", ...];
Example: Creating an array and copying its items to another array, and displaying the copied items.
JavaScript
// Create and initialize an array let courses = [ "HTML" , "CSS" , "JavaScript" , "React" ]; // Display the array items console.log(courses); // Create a new empty array let newArray = []; // forEach loop to push elements // into new array courses.forEach( function (course) { newArray.push(course); }); // Display the new array of items console.log(newArray); |
[ 'HTML', 'CSS', 'JavaScript', 'React' ] [ 'HTML', 'CSS', 'JavaScript', 'React' ]
JavaScript Array Constructor
In JavaScript, a constructor gets called when an object is created using the new keyword.
Constructor |
Descriptions |
Examples |
---|---|---|
Array() | It is used to create an array. |
JavaScript Array Properties
A JavaScript property is a member of an object that associates a key with a value.
Instance Property:
An instance property is a property that has a new copy for every new instance of the class.
Instance Properties |
Descriptions |
Examples |
---|---|---|
constructor | Returns only reference of the function and does not return the name of the function. | |
length | Set or return the number of elements in an array. |
JavaScript Array Methods
JavaScript methods are actions that can be performed on objects.
Static Method:
If the method is called using the array class itself then it is called a static method.
Static Methods |
Descriptions |
Examples |
---|---|---|
from() | Returns an array object from any object with a length property or an iterable object. | |
isArray() | Returns true if the argument passed is an array else it returns false. | |
of() | Creates a new array instance with variables present as the argument of the function. |
Instance Method:
If the method is called on an instance of a array then it is called an instance method.
Instance Methods |
Descriptions |
Examples |
---|---|---|
at() | Returns the element of that index | |
concat() | Merge two or more arrays together. | |
copyWithin() | Copies part of an array to the same array itself and returns. | |
entries() | Fetch all the entries of the same data structure. | |
every() | checks that whether all the elements of the array satisfy the given condition. | |
fill() | Fill the array with a given static value. | |
filter() | Builds a new array containing elements that satisfy a function’s test. | |
find() | Get the value of the first element in the array that satisfies the provided condition. | |
findIndex() | Return the first index of the element in a given array that satisfies the provided testing function. | |
flat() | Flatten an array, to reduce the nesting of an array. | |
flatMap() | This is used to flatten the input array element into a new array. | |
forEach() | It is provided a function once for each element of the array. | |
includes() | If an array contains the certain value, it returns true. | |
indexOf() | Return the first index at which a given element may be found, or -1 if it does not exist. | |
join() | Join the elements of an array into a string. | |
keys() | Return a new array iterator which contains the keys for each index in the given input array. | |
lastIndexOf() | Return the last index at which a given element may be found, or -1 if it does not exist. | |
map() | Calls the argument function once for each element of the given array in order. | |
pop() | Remove the last element of the array and also returns the removed element. | |
push() | Push one or more values into the array. | |
reduce() | Reduce the array to a single value and executes a provided function for each value of the array. | |
reduceRight() | Convert elements of the given array from right to left to a single value. | |
reverse() | This is used for the in-place reversal of the array. | |
shift() | Removes the first element of the array thus reducing the size of the original array by 1. | |
slice() | Returns a new array containing a portion of the array on which it is implemented. | |
some() | Each array element’s callback function is run once. | |
sort() | Sort an array in place in a given order according to the compare() function. | |
splice() | Modify the contents of an array by removing the existing elements. | |
toLocaleString() | Convert the elements of the given array to string. | |
toString() | Return the string representation of the array elements. | |
unshift() | Add one or more elements to the beginning of the given array. | |
values() | Return a new array Iterator object that contains the values for each index in the array. |