How to Trim and Uppercase in Javascript
In this tutorial, you will learn how to trim and uppercase in javascript. Trimming means removing any unnecessary extra space at the beginning and end of the string. For a newbie developer, it can be a bit tricky to trim a string and then convert it into an uppercase.
There are numerous ways to trim and convert a string to an uppercase. But for the sake of simplicity, we will use trim()
method and toUpperCase()
method. The trim()
method removes any extra space at the beginning and at the end of a string. The toUpperCase()
method will convert the string to uppercase.
In the following example, we have one global variable that holds a string. Upon click of a button, we will trim and convert the string to uppercase 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
, andh1
). Thediv
element is just a wrapper for the rest of the elements. - The
innerText
for thebutton
element is“Trim”
and for theh1
element, it is“Result”
. - We have done some basic styling using CSS and added the link to our
style.css
stylesheet inside thehead
element. - We have also included our javascript file
script.js
with ascript
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>Trim</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 andh1
element using thedocument.querySelector()
method and stored them inbtnTrim
andoutput
variables respectively. - We have a global variable
myString
which holds a text as its value. - We are displaying
myString
in theh1
element usinginnerText
property. - We have attached a
click
event listener to thebutton
element. - In the event handler function, we are calling
trim()
method to remove any extra space at the beginning and at the end of the string. Thistrim()
method will return a new string. - We are calling
toUpperCase()
method to convert the trimmed string to uppercase. - We are storing the final string in the
result
variable. - We are displaying the
result
in theh1
element using theinnerText
property.
let btnTrim = document.querySelector("button"); let output = document.querySelector("h1"); let myString = ` BA stands for Bachelor of Arts `; output.innerText = myString; btnTrim.addEventListener("click", () => { let result = myString.trim().toUpperCase(); output.innerText = result; });