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.
// 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);
Output
[ '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 |
|---|---|
| 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 |
|---|---|
| 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 |
|---|---|
| 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 |
|---|---|
| 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. |
