April 26, 2022

How to Check if String Ends with Whitespace in Javascript

By Krishnaa JavaScript Questions 0 Comments

In this tutorial, you will learn how to check if string ends with whitespace in javascript. It is very uncommon to have a whitespace at the end of a string since in most of the cases having a trailing whitespace does not make any sense. Sometimes a trailing space in a string may be present by mistake. For a newbie developer, it can be a bit tricky to find if a string ends with a whitespace.

There are numerous ways to check if a string ends with a whitespace. But for the sake of simplicity, we will use the length property, charAt() method, and ternary operator (?) to accomplish our goal. The length property returns the length of the string. If the string is empty, then it will return 0.

A string consists of multiple characters and these characters in a string have a 0-based index. That means the first character in a string has an index of 0 and to get that character by index, we can use charAt() method.

In the following example, we have one global variable that holds a string. Upon click of a button, we will check if the string ends with a whitespace 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 “Check” 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>Check</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 btnCheck 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 getting the last character from string using charAt() method. By subtracting 1 from the length property, we are passing index of the last character to the charAt() method. The last character is stored in the lastChar variable.
We are checking if the lastChar is equal to a whitespace. This check will give us a Boolean value which we are storing in the found variable.
We are using the ternary operator (?) and checking whether found is true or false. If it is true, that means the string ends with a whitespace.
Depending upon the result of the check, we will assign “Yes” or “No” to the result variable.
We are displaying the result in the h1 element using the innerText property.

let btnCheck = document.querySelector("button");
let output = document.querySelector("h1");

let myString = "Got some whitespace at the end    ";

btnCheck.addEventListener("click", () => {
  let lastChar = myString.length - 1;
  let found = lastChar == " ";
  let result = found ? "Yes" : "No";
  output.innerText = result;
  
});

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