If isNaN() returns false, the value is a number.Another way is to use the typeof operator. It returns the 'number' string if you use it on a number value:typeof 1 //'number' const value = 2 typeof value //'number'So you can do a conditional check like this:const value = 2...
Use parseFloat() to try to convert n to a number. Use !Number.isNaN() to check if num is a number.
The following code shows how to use isNan to check if a value is a number. Example <!DOCTYPEhtml><html><head><scripttype="text/javascript">document.writeln(isNaN("blue"));document.writeln(isNaN("123"));</script><!--www.java2s.com--></head><body></body></html> ...
In JavaScript, a value can either be a primitive or an object. Therefore, you can check if a value is a JavaScript primitive (as opposed to being an object) using the following check: !(value instanceof Object) You may see value !== Object(value) as a means to check for prim...
To check the value for percentage, use a regular expression. When dealing with user input or processing data in JavaScript, it's important to make sure a value is a valid percentage. This article shows you how to check if a value is a percentage using JavaScript, highlighting a useful ...
JavaScript Program to Check if a Number is Float or Integer Write a function to check if a number is odd or even. If the number is even, return"Even"; otherwise, return"Odd". For example, ifnum = 4, the expected output is"Even"....
Check if a Value IsNaNby Using a Comparison Operator in JavaScript The following method is even faster than the ones detailed above, and it also requires less code. On the other hand, it is a bit more confusing, not to mention that it may prove to be hard to maintain and document prop...
In JavaScript, undefined is the default value for variables that have been declared but not initialized. On the other hand, null is an intentional assignment that explicitly indicates the absence of a value. Methods to Check if a Variable is Undefined Using typeof Operator Using Strict Equality...
str = new String("My name is Tom."); if (str instanceof String) { console.log('The variable is a String.'); } else { console.log('The variable is not a String.'); } Output:The variable is a String. JavaScript Examples »...
Vue check value is Integer: Vue.js is a progressive JavaScript framework used for building user interfaces. It provides a convenient way to check if a value is an integer by using the Number.isInteger() method. This method is a built-in JavaScript