js how to tell if a number code example
Example 1: js check if string is number
isNaN(num) // returns true if the variable does NOT contain a valid number
isNaN(123) // false
isNaN('123') // false
isNaN('1e10000') // false (This translates to Infinity, which is a number)
isNaN('foo') // true
isNaN('10px') // true
Example 2: javascript check if variable is number
function isNumber(n) {
return !isNaN(parseFloat(n)) && !isNaN(n - 0);
}