How to check if a number is finite in JavaScript?

Javascript providesisFinite()method to check if the given entity is a valid number. If the given entity is a number, then regardless of the string " 123"What is, this method will causeboolean value true, otherwise returnsfalse. Let's discuss it briefly.

Syntax

isFinite(value);

This method takes a value as a parameter and returns a boolean value true if the passed value is a number, otherwise it returns a boolean value false.

Example1

In the following example,number　sent as a parameter to the methodisFinite()In this case, the result is displayed in the output.

<html>
<body>
<p id="number"></p>
<script>
　　　var a = isFinite(567)　+　"</br>";
　　　var b = isFinite(-9.23)　+　"</br>";
　　　var c = isFinite(0)　+　"</br>";
　　　var d = isFinite(6-7)　+　"</br>";
　　　var bol = a　+　b　+　c　+　d;
　　　document.getElementById("number").innerHTML = bol;
</script>
</body>
</html>

Output Result

true
true
true
true

Example2

In the following example,String　andDate　This method accepts a numeric string as a number and returns true as the output.　

<html>
<body>
<p id="number"></p>
<script>
　　　123)　+　"<br>";
　　　var y = isFinite("string")　+　"<br>";
　　　var z = isFinite("2019/08/06);
　　　var res = x　+　y　+　z ;
　　　document.getElementById("number").innerHTML = res;
</script>
</body>
</html>

Output Result

true
false
false

Basic Tutorial