if string has number javascript 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: how to check if a string contains numbers in javascript

/**
 * Function to check if a string contains numbers
 * @author Okoro Redemption
 * @param {String} str - The string to be checked.
 * @returns {Boolean} str - The result of the check.
 */
function hasNumbers(str){
  var regexp = /d/g;
  return regexp.test(str);
};

// use function below
hasNumbers("I am 20years old"); // => true
hasNumbers("I am a boy"); // => false