This tutorial taught you three different ways to check if a value is a number in JavaScript. You can also run a comparison by writing a conditional statement: var value = 123 if (typeof(value) = "number") ) - true isNaN(2) - false isNaN(2.4) - false Conclusion Instead of providing a boolean response, the value's data type is returned: typeof(123) - number typeof(-123) - number typeof("123") - string typeof() - object The method returns true if the value is numeric, and false if it isn't: Number.isInteger(123) - true Number.isInteger(-123) - true Number.isInteger("123") - false Number.isInteger(4 / 2) - true Number.isInteger(5 / 2) - false The typeof() OperatorĪnother way to check if a value is a number is with the typeof() operator. Luckily for us undefined is a datatype for an undefined value as you can see below: let name console. We can also use the type of the variable to check if it’s undefined. The method returns true if the value is numeric, and false if it isn't: Number. How to Check if a Variable is Undefined in JavaScript with typeof. The isInteger() method in JavaScript accepts a single parameter, the value being tested. The isInteger () method in JavaScript accepts a single parameter, the value being tested. In this tutorial, we'll explore three different ways to check if a value is a number in JavaScript, using the isInteger(), typeof(), and isNaN() methods.
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June 2023
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