June 2, 2022

How to Trim a String Before a Specific Character in Javascript

By Krishnaa JavaScript Questions 0 Comments

In this tutorial, you will learn how to trim a string before a specific character in javascript. Each character in a string has a specific index and we can utilize that index to trim a string. From a developer perspective, it can be a bit tricky to trim a string before a specific character.

There are numerous ways to trim a string before a specific character. A string consists of multiple characters and these characters in a string have a 0-based index. To trim the string, we can make use of the slice() method.

The slice() method takes 2 parameters and they basically specify starting and ending index number of characters in a string for slicing purposes. The second parameter is optional and by default, it is considered to be the length of the string.

In the following example, we have one global variable that holds a string. Upon click of a button, we will trim the string before a specific character 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 indexOf() method to get the index of character "t". We are storing that index in the charIndex variable.
We are calling the slice() method and passing charIndex which is the index of the character "t". As a result, we will get the string the after the character "t" and it 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 = "I never knew that this would happen";

btnGet.addEventListener("click", () => {
  let charIndex = myString.indexOf("t");
  let result = myString.slice(charIndex);
  output.innerText = result;
});

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