How to check if a value is a number using isNumeric in JavaScript?

Are you stuck on finding a solution on how to check if a value is a number using isnumeric in JavaScript?

Look no further because this article gathered all the needed information just for you! So keep reading!

To learn how to check if a value is a number or not in JavaScript.

Before we dive into the solutions, let’s first understand what data types are.

Data Types in JavaScript

In JavaScript, each value is associated with a particular data type. Knowledge of these data types is vital because they serve as the building blocks for various operations, including numeric evaluations.

Here are some essential data types in JavaScript:

What is isnumeric?

The isNumeric is a function that checks if an expression can be evaluated as a number.

It returns a Boolean value indicating whether the expression is numeric or not.

Here’s the example of isnumeric:

isNumeric(10); // true

isNumeric(0144) //true

isNumeric("3.14"); // true

isNumeric("143-5”); // true

isNumeric( 0xFF) // true

isNumeric(+13)  // true

isNumeric("1")  // true



isNumeric(Infinity); // false , use isFinite()

isNumeric(NaN); // false , use isNaN()

isNumeric([0]); // false

isNumeric(true); // false

isNumeric("foo"); // false

isNumeric(null); // false

isNumeric(new Date()); // false

isNumeric( Infinity ) // false

isNumeric( undefined ) // false

isNumeric( "" ) // false

isNumeric( {} ) // false

The isNumeric function is accessible in various programming languages, including Python and Visual Basic for Applications.

In Python, the isnumeric() method serves this purpose, returning a True value when all the characters within a string are numeric (0-9), and False otherwise.

It’s worth noting that exponents, such as ² and ¾, are also considered to be numeric values under this evaluation.

Unfortunately, there is no isNumeric function in JavaScript. Luckily, you can use other methods such as isInteger(), typeof(), isNaN(), and more to check if a value is a number in JavaScript.

In simple words, the isNumeric function is not a built-in feature in JavaScript, but it can be easily implemented to check whether a value is numeric.

Different ways to check isnumeric in JavaScript

Here are some examples of how to check if a value is a number in JavaScript:

Solution 1: Using the isInteger() method

For example:

let samplevalue = 1;
console.log(Number.isInteger(samplevalue));✅

Output:

true

Solution 2: Using the typeof() operator

For example:

let samplevalue = 2;
console.log(typeof samplevalue === 'number');

Output:

true

Solution 3: Using the isNaN() global variable

For example:

let samplevalue = 3;
console.log(!isNaN(samplevalue));

Output:

true

Solution 4: Using the parseFloat() function

For example:

let samplevalue = "4";
console.log(parseFloat(samplevalue) == samplevalue);

Output:

true

Solution 5: Using the parseInt() function

For example:

let samplevalue = "5";
console.log(parseInt(samplevalue) == samplevalue);

Output:

true

Solution 6: Using a regular expression

For example:

let samplevalue = "6";
console.log(/^\d+$/.test(samplevalue));

Output:

true

The list of solutions above is just a few ways to check if a value is a number in JavaScript, and you can use any of these methods depending on your needs.

Examples of Numeric Values in JavaScript

For you to have a better understanding, let’s check out some examples of how to determine if a value is numeric in JavaScript:

Example 1: Numeric Value

For example:

let samplenum = 1;
console.log(!isNaN(samplenum));

Here, we have a number 1 stored in a variable called “samplenum.” To check if “num” is a number, we use a function called isNaN(), which stands for “is Not a Number.”

When we apply isNaN() to “num,” it will give us a response. If “num” is a number, the function will return “false,” meaning it is a valid numeric value. So, in this example, the output will be “true” because “num” is a numeric value.

Output:

true

Example 2: Numeric String

For example:

let strNum = "2.14";
console.log(!isNaN(strNum)); 

Here, we have a variable strNum assigned to the string value “2.14”, which represents a numeric value. By using the isNaN() function, we check if strNum is a numeric value.

As “2.14” can be interpreted as a number, the output will be true.

Output:

true

Example 3: Non-Numeric String

For example:

let nonNumStr = "Itsourcecode";
console.log(!isNaN(nonNumStr));

As you can see, the variable nonNumStr is assigned the string value “Itsourcecode,” which is not a numeric value.

The isNaN() function will return true for non-numeric strings, so the output will be false.

Output:

false

Example 4: Boolean Value

For example:

let samboolValue = true;
console.log(!isNaN(samboolValue));

Here, we have a variable samboolValue assigned to the boolean value true.

Although true and false are represented as 1 and 0 in some contexts, they are not considered numeric values in JavaScript. Therefore, the output will be true.

Output:

true

Example 5: Undefined Value

For example:

let undefinedValue;
console.log(!isNaN(undefinedValue));

Here, we have the variable undefinedValue is not assigned a value, resulting in undefined. Since undefined is not a numeric value, the isNaN() function will return true, and the output will be false.

Output:

false

Example 6: Null Value

For example:

let nullValue = null;
console.log(!isNaN(nullValue));

As you have noticed, the variable nullValue is assigned the value null, which is not a numeric value. Similar to undefined, null is not considered numeric, and the isNaN() function will return true, resulting in an output of false.

Output:

Output: false

Conclusion

In conclusion, this article explains how to check if a value is a number in JavaScript and provides enough solutions using various methods.

While there is no built-in “isNumeric” function in JavaScript, we can utilize other techniques such as “Number.isInteger(),” “typeof(),” “isNaN(),” “parseFloat(),” “parseInt(),” and regular expressions to achieve the desired result.

Using the solutions that this article has already given, you can effectively validate numeric values in your JavaScript code.

We are hoping that this article provides you with enough information that helps you understand the isnumeric in JavaScript.

You can also check out the following article:

• JavaScript tostring
• Array Destructuring JavaScript.
• JavaScript touppercase

Thank you for reading itsourcecoders 😊.

Caren Bautista

Technical Writer at PIES IT Solution

Responsible for crafting clear, well-structured, and beginner-friendly content across the platform. Handles the writing, proofreading, and editorial review of tutorials, guides, and documentation to ensure every article is accurate, readable, and easy to follow.

Expertise: Technical Writing · Content Creation · Documentation · Editorial Writing · JavaScript · TypeScript · Python · Python Errors · HTTP Errors · MS Excel  · View all posts by Caren Bautista →