The isFinite() function determines whether a value is finite, first converting the value to a number if necessary. A finite number is one that's not NaN or ±Infinity. Because coercion inside the isFinite() function can be surprising, you may prefer to use Number.isFinite.
Syntax
isFinite(value)
Parameters
value- : The value to be tested.
Return value
false if the given value is NaN, Infinity, or -Infinity after being converted to a number; otherwise, true.
Description
isFinite() is a function property of the global object.
When the argument to the isFinite() function is not of type Number, the value is first coerced to a number, and the resulting value is then compared against NaN and ±Infinity. This is as confusing as the behavior of isNaN — for example, isFinite("1") is true.
Number.isFinite is a more reliable way to test whether a value is a finite number value, because it returns false for any non-number input.
Examples
Using isFinite()
isFinite(Infinity); // false
isFinite(NaN); // false
isFinite(-Infinity); // false
isFinite(0); // true
isFinite(2e64); // true
isFinite(910); // true
// Would've been false with the more robust Number.isFinite():
isFinite(null); // true
isFinite("0"); // true