Enoch Barcenas

Enoch Barcenas

1585922820

JavaScript Array splice() Method

In this JavaScript tutorial we’re going to learn about the splice JavaScript Array Method and how it can be used to remove or replace existing items and/or add new elements inside an array.

Keep in mind that the splice method will change the array on which is called upon, which might not be the best idea always.

Array.prototype.splice()

The splice() method changes the contents of an array by removing or replacing existing elements and/or adding new elements in place.

JavaScript Demo: Array.splice()

const months = ['Jan', 'March', 'April', 'June'];
months.splice(1, 0, 'Feb');
// inserts at index 1
console.log(months);
// expected output: Array ["Jan", "Feb", "March", "April", "June"]

months.splice(4, 1, 'May');
// replaces 1 element at index 4
console.log(months);
// expected output: Array ["Jan", "Feb", "March", "April", "May"]

Syntax

let arrDeletedItems = array.splice(start[, deleteCount[, item1[, item2[, ...]]]])

Parameters

start

The index at which to start changing the array.

If greater than the length of the array, start will be set to the length of the array. In this case, no element will be deleted but the method will behave as an adding function, adding as many element as item[n*] provided.

If negative, it will begin that many elements from the end of the array. (In this case, the origin -1, meaning -n is the index of the nth last element, and is therefore equivalent to the index of array.length - n.)

If array.length + start is less than 0, it will begin from index 0.

deleteCount | Optional

An integer indicating the number of elements in the array to remove from start.

If deleteCount is omitted, or if its value is equal to or larger than array.length - start (that is, if it is equal to or greater than the number of elements left in the array, starting at start), then all the elements from start to the end of the array will be deleted.

Note: In IE8, it won’t delete all when deleteCount is omitted.

If deleteCount is 0 or negative, no elements are removed. In this case, you should specify at least one new element (see below).

item1, item2, ... | Optional

The elements to add to the array, beginning from start. If you do not specify any elements, splice() will only remove elements from the array.

Return value

An array containing the deleted elements.

If only one element is removed, an array of one element is returned.

If no elements are removed, an empty array is returned.

Description

If the specified number of elements to insert differs from the number of elements being removed, the array’s length will be different at the end of the call.

Examples

Remove 0 (zero) elements before index 2, and insert “drum”

let myFish = ['angel', 'clown', 'mandarin', 'sturgeon']
let removed = myFish.splice(2, 0, 'drum')

// myFish is ["angel", "clown", "drum", "mandarin", "sturgeon"] 
// removed is [], no elements removed

Remove 0 (zero) elements before index 2, and insert “drum” and “guitar”

let myFish = ['angel', 'clown', 'mandarin', 'sturgeon']
let removed = myFish.splice(2, 0, 'drum', 'guitar')

// myFish is ["angel", "clown", "drum", "guitar", "mandarin", "sturgeon"] 
// removed is [], no elements removed

Remove 1 element at index 3

let myFish = ['angel', 'clown', 'drum', 'mandarin', 'sturgeon']
let removed = myFish.splice(3, 1)

// removed is ["mandarin"]
// myFish is ["angel", "clown", "drum", "sturgeon"] 

Remove 1 element at index 2, and insert “trumpet”

let myFish = ['angel', 'clown', 'drum', 'sturgeon']
let removed = myFish.splice(2, 1, 'trumpet')

// myFish is ["angel", "clown", "trumpet", "sturgeon"]
// removed is ["drum"]

Remove 2 elements from index 0, and insert “parrot”, “anemone” and “blue”

let myFish = ['angel', 'clown', 'trumpet', 'sturgeon']
let removed = myFish.splice(0, 2, 'parrot', 'anemone', 'blue')

// myFish is ["parrot", "anemone", "blue", "trumpet", "sturgeon"] 
// removed is ["angel", "clown"]

Remove 2 elements from index 2

let myFish = ['parrot', 'anemone', 'blue', 'trumpet', 'sturgeon']
let removed = myFish.splice(2, 2)

// myFish is ["parrot", "anemone", "sturgeon"] 
// removed is ["blue", "trumpet"]

Remove 1 element from index -2

let myFish = ['angel', 'clown', 'mandarin', 'sturgeon']
let removed = myFish.splice(-2, 1)

// myFish is ["angel", "clown", "sturgeon"] 
// removed is ["mandarin"]

Remove all elements after index 2 (incl.)

let myFish = ['angel', 'clown', 'mandarin', 'sturgeon']
let removed = myFish.splice(2)

// myFish is ["angel", "clown"]
// removed is ["mandarin", "sturgeon"]

#javascript #web-development

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JavaScript Array splice() Method
Ollie  Dietrich

Ollie Dietrich

1626161520

JavaScript Array Methods #6: Array .splice() Method

The JavaScript array splice() method is used to add/remove the elements to/from the existing array. The splice() method also modifies the original array and returns an array of all elements removed from the array. An empty array is returned if no elements are removed.

Syntax:
array.splice(startIndex, deleteCount[, item1, item2, …])

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#javascript #array #splice

Terry  Tremblay

Terry Tremblay

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Fill and Filter in Array in JavaScript

By the word Array methods, I mean the inbuilt array functions, which might be helpful for us in so many ways. So why not just explore and make use of them, to boost our productivity.

Let’s see them together one by one with some amazing examples.

Array.fill():

The _fill()_ method changes all elements in an array to a static value, from a start index (default _0_) to an end index (default _array.length_). It returns the modified array.

In simple words, it’s gonna fill the elements of the array with whatever sets of params, you pass in it. Mostly we pass three params, each param stands with some meaning. The first param value: what value you want to fill, second value: start range of index(inclusive), and third value: end range of index(exclusive). Imagine you are going to apply this method on some date, so that how its gonna look like eg: array.fill(‘Some date’, start date, end date).

NOTE: Start range is inclusive and end range is exclusive.

Let’s understand this in the below example-

//declare array
var testArray = [2,4,6,8,10,12,14];

console.log(testArray.fill("A"));

When you run this code, you gonna see all the elements of testArray will be replaced by 'A' like [“A”,"A","A","A","A","A","A"].

#javascript-tips #array-methods #javascript-development #javascript #arrays

Lowa Alice

Lowa Alice

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JavaScript Arrays Tutorial. DO NOT MISS!!!

Learn JavaScript Arrays

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#arrays #javascript #javascript arrays #javascript arrays tutorial

Tanya  Shields

Tanya Shields

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Learn Arrays And Array Methods in JavaScript

In JavaScript, an array is a data structure that contains list of elements which store multiple values in a single variable. The strength of JavaScript arrays lies in the array methods. Array methods are functions built-in to JavaScript that we can apply to our arrays — Each method has a unique function that performs a change or calculation to our array and saves us from writing common functions from scratch.
In this video we are going to learn arrays and array methods like sort(), reverse(), join(), split(), pop(), push(), shift(), unshift(), toString(), delete array, etc…

#javascript #arrays #array methods #programming

Madilyn  Kihn

Madilyn Kihn

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Convert String To Array Using Javascript Split Method

The easiest approach to use javascript built-in method String.split().

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