JavaScript Array splice() Method

JavaScript Array splice() Method

In this tutorial, we would love to share with you how to remove the elements/items from the javascript array. We will describe splice() methods of javaScript to removing/adding the elements/items in an array.

In this tutorial, we would love to share with you how to remove the elements/items from the javascript array. We will describe splice() methods of javaScript to removing/adding the elements/items in an array.

In this tutorial, we will take several examples of the JavaScript splice() method for better demonstration.

JavaScript splice() method definition

The javascript splice() method is used to add or remove elements/items from an array.

Syntax of javascript splice() method

array.splice(index, howmany, item1, ....., itemX)
  • The first argument specifies the location at which to begin adding or removing elements.
  • The second argument specifies the number of elements to remove.
  • The third and subsequent arguments are optional; they specify elements to be added to the array.

Now we will take several examples of splice() method:

Example1 -Remove 2 elements from index 2

Let’s take an example, Suppose we have one array that names arr, we want to remove the elements in it. So let’s see the example below:

  var arr = ['Cabbage', 'Turnip', 'Radish', 'Carrot'];

  arr.splice(1,2);

  console.log( arr ); 

Result of the above example-1 is:

["Cabbage", "Carrot"] 

Example2 – Add new element from index 0

Let’s take new an example, Suppose we have one array that names arr.

If you want to add the elements in arr array. So let’s see the example below:

  var arr = ['Cabbage', 'Turnip', 'Radish', 'Carrot'];

  arr.splice(0,0,"zero");

  console.log( arr ); 

Result of the above example-2 is:

["zero", "Cabbage", "Turnip", "Radish", "Carrot"]

At position 0, add the new items.

Example3 – Add and Remove Elements in Array

In this example, we will demonstrate how to add and remove the array.

Suppose, you have an array that name month. In this array, you want to add/remove the new items/elements. We will demonstrate how to add or remove the item in it. let’s see below example:

var months = ['Jan', 'March', 'April', 'June'];

months.splice(1, 0, 'Feb'); // add at index 1

console.log(months); 

months.splice(4, 1, 'May'); // replaces 1 element at index 4

console.log(months);

Result of the above example-3 is:

 // expected output: Array ['Jan', 'Feb', 'March', 'April', 'June']

 // expected output: Array ['Jan', 'Feb', 'March', 'April', 'May']

Example4 – Remove all elements after index 3

In this example, we will explain how to remove all the elements after particular index from an array. Let’s see the example below:

  var arr = [ "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten" ]; 

 arr.splice(3);

 console.log( arr );  

Result of the above example-4 is:

 [ "one", "two", "three"]; 

Example-5 Replaces 1 element at index 5

In this example, we will demonstrate how to replace the value of an array. Let’s see the below example

 var arr = [ "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten" ]; 

 arr.splice(5,1,6);

 console.log( arr );  

Result of the above example-5 is:

["one", "two", "three", "four", "five", 6, "seven", "eight", "nine", "ten"]

How do I remove an object from an array with JavaScript?

Using the javascript splice() method to remove Objects from Array in JavaScript. Let’s see the example below.

We have an array object, we want to remove the id=3 object inside the array. So use the below method:

var arr = [
 {id:1,name:'hello'}, 
 {id:2,name:'world'},
 {id:3,name:'cool'},
 {id:4,name:'javascript'},
 {id:5,name:'jquery'}
 ];
 var ind = arr.findIndex(function(element){
    return element.id===3;
 })
 if(ind!==-1){
 arr.splice(ind, 1)
 }
 console.log (arr);

Let’s take second of example remove the object from JSON array in javascript. Let’s see the example below

var arr = [
 {id:1,name:'hello'}, 
 {id:2,name:'world'},
 {id:3,name:'cool'},
 {id:4,name:'javascript'},
 {id:5,name:'jquery'}
 ];
 arr.splice(arr, 4);
 console.log (arr);

Conclusion

In this tutorial, you have learned how to extract/remove, add elements from JavaScript arrays using the splice() method.

Programming a Javascript Simon Game Tutorial

Programming a Javascript Simon Game Tutorial

In this javascript tutorial, I recorded myself live programming an html5 javascript simon game.

In this javascript tutorial, I recorded myself live programming an html5 javascript simon game.

For those who don't know, I'm a full stack web developer who has been in the industry for over 5 years now. There is a lot of things I have learned along the way and I'd like to share that knowledge with anyone wanting to learn!

like this video if you found it useful and would like to see more videos of the same content.

subscribe to my channel if you are trying to improve your abilities as a web developer, software engineer, or even if you are just learning to code.

Don't forget to turn on those bell notifications!

Understanding Memoization And Dynamic Programming in Javascript

Understanding Memoization And Dynamic Programming in Javascript

In this Javascript tutorial I will explain what memoization is, how to use it, when you should use memoization, how to use memoization, what dynamic programming is, how to use memoization in dynamic programming. Memoization is a big complicated word that you may have never even heard before, but you may be surprised to know that you are most likely already using memoization without even realizing it.

Memoization is a big complicated word that you may have never even heard before, but you may be surprised to know that you are most likely already using memoization without even realizing it. Memoization is just the act of caching values so that they can be calculated quicker in the future. Memoization is really useful in all parts of programming, but where it is most useful is in dynamic programming. In this video I will explain what memoization is, how to use it, and why it is so useful especially in dynamic programming.

🧠 Concepts Covered:

  • What memoization is
  • When you should use memoization
  • How to use memoization
  • What dynamic programming is
  • How to use memoization in dynamic programming

JavaScript Tutorial: if-else Statement in JavaScript

JavaScript Tutorial: if-else Statement in JavaScript

This JavaScript tutorial is a step by step guide on JavaScript If Else Statements. Learn how to use If Else in javascript and also JavaScript If Else Statements. if-else Statement in JavaScript. JavaScript's conditional statements: if; if-else; nested-if; if-else-if. These statements allow you to control the flow of your program's execution based upon conditions known only during run time.

Decision Making in programming is similar to decision making in real life. In programming also we face some situations where we want a certain block of code to be executed when some condition is fulfilled.
A programming language uses control statements to control the flow of execution of the program based on certain conditions. These are used to cause the flow of execution to advance and branch based on changes to the state of a program.

JavaScript’s conditional statements:

  • if
  • if-else
  • nested-if
  • if-else-if

These statements allow you to control the flow of your program’s execution based upon conditions known only during run time.

  • if: if statement is the most simple decision making statement. It is used to decide whether a certain statement or block of statements will be executed or not i.e if a certain condition is true then a block of statement is executed otherwise not.
    Syntax:
if(condition) 
{
   // Statements to execute if
   // condition is true
}

Here, condition after evaluation will be either true or false. if statement accepts boolean values – if the value is true then it will execute the block of statements under it.
If we do not provide the curly braces ‘{‘ and ‘}’ after if( condition ) then by default if statement will consider the immediate one statement to be inside its block. For example,

if(condition)
   statement1;
   statement2;

// Here if the condition is true, if block 
// will consider only statement1 to be inside 
// its block.

Flow chart:

Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate If statement 

var i = 10; 

if (i > 15) 
document.write("10 is less than 15"); 

// This statement will be executed 
// as if considers one statement by default 
document.write("I am Not in if"); 

< /script> 

Output:

I am Not in if
  • if-else: The if statement alone tells us that if a condition is true it will execute a block of statements and if the condition is false it won’t. But what if we want to do something else if the condition is false. Here comes the else statement. We can use the else statement with if statement to execute a block of code when the condition is false.
    Syntax:
if (condition)
{
    // Executes this block if
    // condition is true
}
else
{
    // Executes this block if
    // condition is false
}


Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate If-else statement 

var i = 10; 

if (i < 15) 
document.write("10 is less than 15"); 
else
document.write("I am Not in if"); 

< /script> 

Output:

i is smaller than 15
  • nested-if A nested if is an if statement that is the target of another if or else. Nested if statements means an if statement inside an if statement. Yes, JavaScript allows us to nest if statements within if statements. i.e, we can place an if statement inside another if statement.
    Syntax:
if (condition1) 
{
   // Executes when condition1 is true
   if (condition2) 
   {
      // Executes when condition2 is true
   }
}

Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate nested-if statement 

var i = 10; 

if (i == 10) { 

// First if statement 
if (i < 15) 
	document.write("i is smaller than 15"); 

// Nested - if statement 
// Will only be executed if statement above 
// it is true 
if (i < 12) 
	document.write("i is smaller than 12 too"); 
else
	document.write("i is greater than 15"); 
} 
< /script> 

Output:

i is smaller than 15
i is smaller than 12 too
  • if-else-if ladder Here, a user can decide among multiple options.The if statements are executed from the top down. As soon as one of the conditions controlling the if is true, the statement associated with that if is executed, and the rest of the ladder is bypassed. If none of the conditions is true, then the final else statement will be executed.
if (condition)
    statement;
else if (condition)
    statement;
.
.
else
    statement;


Example:

<script type = "text/javaScript"> 
// JavaScript program to illustrate nested-if statement 

var i = 20; 

if (i == 10) 
document.wrte("i is 10"); 
else if (i == 15) 
document.wrte("i is 15"); 
else if (i == 20) 
document.wrte("i is 20"); 
else
document.wrte("i is not present"); 
< /script> 

Output:

i is 20