How to Check if String is Empty in Javascript
In this tutorial, you will learn how to check if string is empty in javascript. A string is considered to be empty when it does not have any characters or content in it and as a result, the length of that string will always be 0.
There are certain primitive types in javascript and string is one of them. As the name suggests, any variable that holds a plain text as its value is considered to be of string type.
There are numerous ways to detect whether a string is empty or not. But for the sake of simplicity, we will use a strict equality operator (===
) to accomplish our goal.
In the following example, we have one global variable that holds a string. Upon click of a button, we will check whether it is empty or not 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“Check”
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>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 andh1
element using thedocument.querySelector()
method and stored them inbtnCheck
andoutput
variables respectively. - We have attached a
click
event listener to thebutton
element. - We have a global variable
myString
which holds an empty string as its value. - In the event handler function, we are using a strict equality operator (
===
) to verify whethermyString
is empty or not. Depending upon the result of the check, we will assign“Yes”
or“No”
to theresult
variable. - We are displaying the
result
in theh1
element using theinnerText
property.
let btnCheck = document.querySelector("button"); let output = document.querySelector("h1"); let myString = ""; btnCheck.addEventListener("click", () => { let result = myString === "" ? "Yes" : "No"; output.innerText = result; });