How to Add Letter to a String in Javascript

In this tutorial, you will learn how to add letter to a string in javascript. Multiple characters, including but not limited to letters, numerals, punctuation, and special characters, are used to create a string. In a string, each character has a particular significance. For a newbie developer, it can be a bit tricky to add a letter to a string.

There are numerous ways to add a letter to a string. But for the sake of simplicity, we will make use of template string which helps in creating a dynamic string by using variables in it.

In the following example, we have two global variables, one is holding a string and another one a letter. Upon click of a button, we will add a letter to a string and display the result on the screen.  Please have a look over the code example and the steps given below.


  • We have 3 elements in the HTML file (divbutton, and h1). The div element is just a wrapper for the rest of the elements.
  • The innerText for the button element is “Add” and for the h1 element, it is “Result”.
  • We have done some basic styling using CSS and added the link to our style.css stylesheet inside the head element.
  • We have also included our javascript file script.js with a script tag at the bottom.
<!DOCTYPE html>
<html lang="en">

  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <link rel="stylesheet" href="style.css">


  <div class="container">    

  <script src="script.js"></script>

.container {        
    text-align: center;

button {
  margin-top: 10px;
  padding: 10px 20px;


  • We have selected the button element and h1 element using the document.querySelector() method and stored them in btnAdd and output variables respectively.
  • We have two global variables str and letter where one variable holds a string and another one a letter.
  • We have attached a click event listener to the button element.
  • In the event handler function, we are creating a string dynamically where we we are using global variables str and letter .
  • We are storing the final string in the result variable.
  • We are displaying the result in the h1 element using the innerText property.
let btnAdd = document.querySelector("button");
let output = document.querySelector("h1");

let str = "Keep Movin";
let letter = "g";
btnAdd.addEventListener("click", () => {  
  let result = `${str}${letter}`;
  output.innerText = result;