emerie111/regex

This is a code used to match and check for the validity of regex patterns.

The script is attached to a HTML file containing some code that enables end user access. In the code snippet, there is a button with onclick attribute, which calls the validate() function when clicked. Inside the validate() function, I used the getElementById method to get the value of the input element and store it in the input variable. Then we use the validateMastercard(input) function to check if the input is a valid Mastercard credit card number and display the appropriate message in the output div using innerHTML property.

The regular expression /^(?:5[1-5][0-9]{14})$/ is used to match a Mastercard credit card number.

Here is a breakdown of the different parts of the regular expression:

-^: This is called an anchor, it matches the start of the string. -(?:5[1-5]): This is a non-capturing group, it matches the first digit of the card number, which should be a 5. The [1-5] after the 5 specifies that the second digit should be between 1 and 5. -[0-9]{14}: This matches the remaining 14 digits of the card number, which should be any digit between 0 and 9. -$: This is another anchor, it matches the end of the string. Combined, this regular expression will match any string that starts with a 5, followed by a digit between 1 and 5, and then 14 more digits between 0 and 9.