isNaN ? code example

Example 1: compare NaN in javascript if condititon

// Use isNaN() 
// In javascript compare NaN direct alweys return false
let num1 = Number("Vishal");

// This code never work
if(num1 == NaN){  // Direct compare NaN alweys return false so use isNaN() function
  ....... Your Code .......
}  

// This code work
if(isNaN(num1){
  .........Your Code .......
}

Example 2: javascript check if is nan

function isNaN(x) {
   return x !== x;
};
isNaN(NaN);//true

Example 3: isNan

const fail = 10 / "zero"; 
console.log(fail); //   NaN (Not a Number)
console.log(isNaN(fail)); // true
console.log(isNaN(10)); // false
console.log(isNaN('10')); // false
console.log(isNaN('blabla')); // true
console.log(isNaN(true)); // false
console.log(1.7976931348623157e+308 * 1000); //  Infinity
console.log(1.7976931348623157e+308 * -1000); // - Infinity
console.log(10 / 0); // Infinity
console.log(isFinite(123)); // true

Example 4: isNaN

function milliseconds(x) {
  if (isNaN(x)) {
    return 'Not a Number!';
  }
  return x * 1000;
}

console.log(milliseconds('100F'));
// expected output: "Not a Number!"

console.log(milliseconds('0.0314E+2'));
// expected output: 3140