check string contains only numbers javascript code example

Example 1: check if string only contains integer digits numbers javascript

let val = '1234567890' 
let isnum = /^\d+$/.test(val);
if (isnum) {
  // val is a number
}

Example 2: javascript check if string includes numbers

/**
 * Function to check if a string contains any numbers
 * @author Sebastian Keable
 * @param {String} str - String to be checked.
 * @returns {Boolean} str - Result of the check.
 */
function containsNumbers(str){
  var regexp = /\d/g;
  return regexp.test(str);
};

// use function below
containsNumbers("Here are some Numbers 2123"); // => true
containsNumbers("Here are no Numbers"); // => false

Example 3: 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