April 28, 2022

How to Trim Last 3 Characters in Javascript

By Krishnaa JavaScript Questions 0 Comments

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;
});

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