javascript check if number or string code example

Example 1: javascript check if string is number

// native returns true if the variable does NOT contain a valid number
isNaN(num)

// can be wrapped for making simple and readable
function isNumeric(num){
  return !isNaN(num)
}

isNumeric(123)         // true
isNumeric('123')       // true
isNumeric('1e10000')   // true (This translates to Infinity, which is a number)
isNumeric('foo')       // false
isNumeric('10px')      // false

Example 2: javascript check if string is number

function isNumeric(num){
  return !isNaN(num)
}
isNumeric("23.33"); //true, checking if string is a number.

Example 3: if parameter is not number in js

let num1 = 'Hello';
if(isNaN(num1)){
    console.log(num1 + ' is not a number');
} else{
    console.log(num1 + ' is a number');
}

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