Javascript Regex to validate string length and last 3 characters as digits

Question

How should I write regex to validate below conditions:

• Total length of string should be between 4 to 6
• Last 3 characters should be digits only.
• String is only alphanumeric

eg: Valid strings: 1234, EC123, 1YC898, 001234

So far, I have tried below regex, but seems like I am missing something?

(^[a-zA-Z0-9]{4,6})?\d{3}$

Answer 1

You can use:

^[a-zA-Z0-9]{1,3}\d{3}$

• ^[a-zA-Z0-9]{1,3} will match 1 to 3 alpha-numerals at the start
• \d{3}$ will match 3 digits at the end of your input