Using JavaScript to Check if String Contains Numbers

There are many ways we can use JavaScript to check if a string contains numbers. We will go over two simple methods below to do this.

The first uses the JavaScript test() method and a regex expression.

/d/.test(someString);

The regex expression /d/ will check for any number from 0-9. The test() method will check the string you pass as a parameter to see if a number is contained in the string due to the regex expression. If it does find it, it returns true. Otherwise, it returns false.

We can wrap this code in a function to make it easy to reuse.

function stringContainsNumber(str){
  return /d/.test(str);
};

Now let’s test this function with a couple of examples:

function stringContainsNumber(str){
  return /d/.test(str);
};

var string1 = "This is a string with no numbers";
var string2 = "This is a string with numbers 1234567890";
var string3 = "This is a string a number 1";
var string4 = "123456";
var string5 = 12;

console.log(stringContainsNumber(string1));
console.log(stringContainsNumber(string2));
console.log(stringContainsNumber(string3));
console.log(stringContainsNumber(string4));
console.log(stringContainsNumber(string5));

#Output
false
true
true
true
true

Using JavaScript match() Method to Check if String Contains Numbers

We can also use the match() method to check if a string contains numbers along with a regex expression as we did with the test method.

someString.match(/d/);

The match() method will search the string, someString, for whatever you pass in as the parameter, which in this case is our regex expression for a number. The match() method will return an array with all of the matches, otherwise if a match is not found, it will return null.

Let’s put this code in a function as we did with the test() method.

function stringContainsNumber(str){
  if( str.match(/d/) != null ){
    return true;
  } else {
    return false;
  }
};

And finally, let’s test this function as we did with our first function.

Now let’s test this function with a couple of examples:

function stringContainsNumber(str){
  if( str.match(/d/) != null ){
    return true;
  } else {
    return false;
  }
};

var string1 = "This is a string with no numbers";
var string2 = "This is a string with numbers 1234567890";
var string3 = "This is a string a number 1";
var string4 = "123456";

console.log(stringContainsNumber(string1));
console.log(stringContainsNumber(string2));
console.log(stringContainsNumber(string3));
console.log(stringContainsNumber(string4));

#Output
false
true
true
true

Hopefully this article has been useful for you to learn how to use JavaScript to check if a string contains numbers.