How to Trim Last 3 Characters in Javascript

In this tutorial, you will learn how to trim last 3 characters in javascript. The last 3 characters in a string can be letters, numbers, or special characters. For a newbie developer, it can be a bit tricky to trim last 3 characters of a string.

There are numerous ways to trim the last 3 characters of a string. We are going to use one of the easiest solutions which involve the usage of the length property and substring() method. A string consists of multiple characters and these characters in a string have a 0-based index. With the help of substring() method, we can get the rest of the string after trimming the last 3 characters.

The length property of a string returns the number of total characters in that string. To get the index of the third last character in the string, we just need to subtract 3 from the length.

In the following example, we have one global variable that holds a string. Upon click of a button, we will trim the last 3 characters of the string and display the result on the screen.  Please have a look over the code example and the steps given below.

HTML & CSS

  • We have 3 elements in the HTML file (div, button, and h1). The div element is just a wrapper for the rest of the elements.
  • The innerText for the button element is “Get” 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">

<head>
  <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">
  <title>Document</title>
</head>

<body>

  <div class="container">    
    <button>Get</button>
    <h1>Result</h1>
  </div>

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

</html>
.container {        
    text-align: center;
}

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

Javascript

  • We have selected the button element and h1 element using the document.querySelector() method and stored them in btnGet and output variables respectively.
  • We have attached a click event listener to the button element.
  • We have a global variable myString which holds a string as its value.
  • In the event handler function, we are calling the substring() method and passing 2 parameters, the index of the third last character and 0 which is the index of the first character. To get the index of the third last character, we just need to subtract 3 from the string length. Finally, we will get a new string except for the last 3 characters "ood". The new string will be stored in the result variable.
  • We are displaying the result in the h1 element using the innerText property.
let btnGet = document.querySelector("button");
let output = document.querySelector("h1");

let myString = "Ron does not look good";

btnGet.addEventListener("click", () => {  
  let result = myString.substring(myString.length - 3, 0);
  output.innerText = result;
});