How to Check if a String Contains a Number in Javascript
In this tutorial, you will learn how to check if a string contains a number in javascript. A number is nothing more than an arithmetic value that is used for representing the quantity and performing certain calculations. A number is formed by the combination of digits from 0 to 9.
There are numerous ways to check if a string contains a number. 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 contains a number 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/\d/
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 thehasNumbers
variable. - We are using the ternary operator (
?
) and checking whetherhasNumbers
is true or false. 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 = "Hello Worl12d"; let regExp = /\d/; btnCheck.addEventListener("click", () => { let hasNumbers = regExp.test(myString) let result = hasNumbers ? "Yes" : "No"; output.innerText = result; });