How to check if a character is a letter or number in JavaScript?

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To check character is a letter or number, JavaScript provides the isNaN() method just pass your character as a parameter it will check character is NaN ( Not a number ) when it returns false means the character is a number else validate the character with regex code /^[a-zA-Z]+$/ to check is a letter or not.

Today, I’m going to show How do I check if a character is a letter or number in Javascript, here I will use the javascript string isNaN() method, and regex code /^[a-zA-Z]+$/` to check if a character is a letter or number.

What is a isNaN() method?

The isNaN() function determines whether a value is NaN or not. Because coercion inside the isNaN function can be surprising, you may alternatively want to use Number.isNaN().

What is a regex code /^[a-zA-Z]+$/?

This regex code is a format of string letter, using this regex code we are able to validate character is a letter or not.

Let’s start the today’s tutorial How do you check if a character is a letter or number in JavaScript?

In the following example, we will check whether a character is a number or not using the isNaN() method when a character is a not a number we will use our regex code to check character is a letter or not.

Copy 
1// Example of character is a letter
2const str1 = "infinitbility";
3
4if(!isNaN(str1)){
5  console.log('✅ character is a number')
6} else if(/^[a-zA-Z]+$/.test(str1)) {
7  console.log('✅ character is a letter')
8}
9
10// Example of character is a Number
11const str2 = "903";
12
13if(!isNaN(str2)){
14  console.log('✅ character is a number')
15} else if(/^[a-zA-Z]+$/.test(str2)) {
16  console.log('✅ character is a letter')
17}

In the above program, we take example of both if string is a letter or string is a number, let’s check the output.

I hope it’s help you, All the best 👍.