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JavaScript isFinite() function

Description

The isFinite is used to determine whether a specified number is finite or not. isFinite is a top-level function and is not associated with any object.

Syntax

isFinite(number)

Parameters

number: The number to evaluate.

Note that the function returns false if the argument is NAN, positive infinity or negative infinity otherwise it returns true.

Example of isFinite() function

The following example shows how to use the isFinite() function.

JavaScript Code:

console.log(isFinite("Good Morning"));
console.log(isFinite("2009/01/01"));
console.log(isFinite(455));
console.log(isFinite(-9.34));
console.log(isFinite(15-12));
console.log(isFinite(0));

View the example in the browser

Live demo:

See the Pen isfinite-function-1 by w3resource (@w3resource) on CodePen.


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Next: JavaScript: isNaN() function



JavaScript: Tips of the Day

semicolon (;)

function nums(a, b) {
  if (a > b) console.log('a is bigger');
  else console.log('b is bigger');
  return;
  a + b;
}

console.log(nums(4, 2));
console.log(nums(1, 2));

In JavaScript, we don't have to write the semicolon (;) explicitly, however the JavaScript engine still adds them after statements. This is called Automatic Semicolon Insertion. A statement can for example be variables, or keywords like throw, return, break, etc.
Here, we wrote a return statement, and another value a + b on a new line. However, since it's a new line, the engine doesn't know that it's actually the value that we wanted to return. Instead, it automatically added a semicolon after return. You could see this as:

return;
a + b;
This means that a + b is never reached, since a function stops running after the return keyword. If no value gets returned, like here, the function returns undefined. Note that there is no automatic insertion after if/else statements!

Ref: https://bit.ly/3jFRBje