How to insert a string at a specific index in JavaScript

Today I'm going to talk about how to insert a string at a specific index in JavaScript. There are two main methods that can be used for this: the slice() method and the splice() method. Let’s take a look at each one in more detail so you can decide which one is best for your project.

Using the slice() method. #

The first option is using the slice() method, which allows you to extract part of an array or string and create new strings without modifying the original array or string.

To use it, simply specify where you want to start slicing from as well as what position should mark its end (the last character won't be included).

Afterward, add whatever text or characters that need inserting between those two positions; then combine them into one single string with concat() method.

<script>
   let myString = "Hello"; // Original String 
   let result = myString.slice(0 , 5) + ' World';
   console.log(result);    
   // Output : Hello World!
</script>

Using the splice() method. #

The second option involves using splice(), which works similarly but has some additional features such as removing elements from existing arrays or strings while adding new ones instead of just replacing them like when using slice().

This time around, all three parameters must be specified—start position (where insertion begins), number of items being removed (use 0 if none), and any items added afterward (separated by commas).

<script>
   let myArray = ["red", "green", "blue"];
       myArray.splice(2 , 0 , "yellow" );         		            
       console.log(myArray);     
       /* Output : ['red', 'green', 'yellow', 'blue'] */
</script>