JAVASCRIPT

check if a variable is a number in javascript

// as test cases we have two variables of which 1 is a number and the second one is a string
let x = 7;
let y = "hello"
let result1 = !Number.isNaN(x) // true
let result2 = !Number.isNaN(y) // flase

javascript check if variable is number

function isNumber(n) {
  return !isNaN(parseFloat(n)) && !isNaN(n - 0);
}

verify if something is a number javascript

// parseInt is one of those things that you say wtf javascript?
//if you pass to it any argument with number first and letters after, it
// will pass with the first numbers and say yeah this a number wtf?
let myConvertNumber = parseInt('12wtfwtfwtf');
console.log(myConvertNumber);
// the result is 12 and no error is throw or something
//but this
let myConvertNumber = parseInt('wtf12wtf');
console.log(myConvertNumber);
// is NaN wtf?
//if you truly want an strict way to know if something is really a real number
// use Number() instead
let myConvertNumber = Number('12wtf');
console.log(myConvertNumber);
// with this if the string has any text the result will be NaN