Javascript: Regex to exclude whitespace and special characters

Question

I need a regex to validate,

1. Should be of length 18
2. First 5 characters should be either (xyz34|xyz12)
3. Remaining 13 characters should be alphanumeric only letters and numbers, no whitespace or special characters is allowed.

I have a pattern like here, '/^(xyz34|xyz12)((?=.*[a-zA-Z])(?=.*[0-9])){13}/g'

But this is allowing whitespace and special characters like ($,% and etc) which is violating the rule #3.

Any suggestion to exclude this whitespace and special characters and to strictly check that it must be letters and numbers?

Answer 1

.* will match any string, for your requirment you can use this:

/^xyz(34|12)[a-zA-Z0-9]{13}$/g

regex fiddle

Answer 2

/^(xyz34|xyz12)[a-zA-Z0-9]{13}$/

This should work,

• ^ asserts position at the start of a line
• 1st Capturing Group (xyz34|xyz12)
  • 1st Alternative xyz34 matches the characters xyz34 literally (case sensitive)
  • 2nd Alternative xyz12 matches the characters xyz12 literally (case sensitive)
• Match a single character present in the list below [a-zA-Z0-9]{13}
• {13} Quantifier — Matches exactly 13 times

Answer 3

You should not quantify lookarounds. They are non-consuming patterns , ie the consecutive positive lookaheads check the presence of their patterns but do not advance the regex index , they check the text at the same position . It makes no sense repeating them 13 times. ^(xyz34|xyz12)((?=.*[a-zA-Z])(?=.*[0-9])){13} is equal to ^(xyz34|xyz12)(?=.*[a-zA-Z])(?=.*[0-9]) , and means the string can start with xyz34 or xyz12 and then should have at least 1 letter and at least 1 digits.

You may consider fixing the issue by using a consuming pattern like this:

• If you do not care if the last 13 chars contain only digits or only letters, use the patterns suggested by other users, like /^(?:xyz34|xyz12)[a-zA-Z\d]{13}$/ or /^xyz(?:34|12)[a-zA-Z0-9]{13}$/
• If there must be at least 1 digit and at least 1 letter among those 13 alphanumeric chars, use /^xyz(?:34|12)(?=[a-zA-Z]*\d)(?=\d*[a-zA-Z])[a-zA-Z\d]{13}$/ .

See the regex demo #1 and the regex demo #2 .

NOTE : these are regex literals, do not use them inside single- or double quotes!

Details

• ^ - start of string
• xyz - a common prefix
• (?:34|12) - a non-capturing group matching 34 or 12
• (?=[a-zA-Z]*\d) - there must be at least 1 digit after any 0+ letters to the right of the current location
• (?=\d*[a-zA-Z]) - there must be at least 1 letter after any 0+ digtis to the right of the current location
• [a-zA-Z\d]{13} - 13 letters or digits
• $ - end of string.

JS demo:

 var strs = ['xyz34abcdefghijkl1','xyz341bcdefghijklm','xyz34abcdefghijklm','xyz341234567890123','xyz14a234567890123']; var rx = /^xyz(?:34|12)(?=[a-zA-Z]*\d)(?=\d*[a-zA-Z])[a-zA-Z\d]{13}$/; for (var s of strs) { console.log(s, "=>", rx.test(s)); }