check if number is nan js code example

Example 1: isnan in javascript

var s = userInput[0];
  if(isNaN(s) !== true)
  {
      console.log("yes");
  }
  else
  {
      console.log("no");
  }

Example 2: javascript check if is nan

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

Example 3: check if value is NaN

Number.isNaN(123)

Example 4: check if var is NaN

let b=1
let n=readline()
if(isNaN(b)){
  console.log("You typed 0!")
}else{
  console.log("You did not type 0!")
}