How to Check if String has No Letters in Javascript
In this tutorial, you will learn how to check if string has no letters in javascript. Letters play an important role in the formation of a word and with the help of those words, we can create meaningful sentences.
There are numerous ways to check if a string has no letters. But for the sake of simplicity, we will use the regular expression and ternary operator (?
) to accomplish our goal. The test()
method of RegExpObject is used to perform a pattern search in a string and returns a Boolean value.
In the following example, we have one global variable that holds a string. Upon click of a button, we will check if the string has no letters 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 a string as its value. - We have the
regExp
variable which holds a regular expression/^[^a-zA-Z]+$/
as its value. - In the event handler function, we are calling the
test()
method ofregExp
and passingmyString
as a parameter. It will return a Boolean value which we are storing in thenoLetters
variable. - We are using the ternary operator (
?
) and checking whethernoLetters
is true or false. If it is true, that meansmyString
has no letters. - Depending upon the result of the check, we will assign
“No Letters”
or“Letters”
to theresult
variable. - We are displaying the
result
in theh1
element using theinnerText
property.
let btnCheck = document.querySelector("button"); let output = document.querySelector("h1"); let myString = "Hello World"; let regExp = /^[^a-zA-Z]+$/; btnCheck.addEventListener("click", () => { let noLetters = regExp.test(myString) let result = noLetters ? "No Letters" : "Letters"; output.innerText = result; });