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JavaScript Regular Expressions in JavaScript Validating a Form Validating a Password

karan karan
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karan karan
Web Development Techdegree Student 12,697 Points

Define length for password

How to define length for password, That this should be at least the length of the password? I tried looking up online for this, but did not get it

^(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).*$

can somebody explain this,

1 Answer

Brian Jensen
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Brian Jensen
Treehouse Staff

Hiya karan karan :wave:

This RegEx that you added to your post, is checking if there is at least one of each of a lowercase letter, uppercase letter and a number:

/^(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).*$/

If you wanted to also add a minimum and maximum password length, you can use a Quantifier. For example if you wanted the password to have a minimum length of 8 characters and a maximum of 20, as well as still ensuring that there is at least one of each of a lowercase letter, uppercase letter and a number, you would change the RegEx to this:

/^(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{8,20}$/