js check if string contains 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: check if a string contains digits js

function hasNumber(myString) {
  return /\d/.test(myString);
}

Example 3: js string have number js

var hasNumber = /\d/;   
      hasNumber.test("ABC33SDF");  //true
      hasNumber.test("ABCSDF");  //false

Example 4: 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 5: 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