Javascript regular expression

Question

I am making form and there is only one more thing which I cant figure it out :(

I need regular expression for password which must be at least 7 characters long. There can be small and big letters and must contain at least one number.

I tried

[0-9]+[a-zA-Z]){7}$

This looks pretty close to what you seek.

DOK
– DOK

2013-06-01 18:59:20 +00:00
Commented Jun 1, 2013 at 18:59 — DOK
– DOK, Commented Jun 1, 2013 at 18:59

PointedEars · Accepted Answer · 2013-06-01 21:50:03Z

4

You can use lookahead:

^(?=.*\d)[a-zA-Z\d]{7,}$

(?=.*\d) is a lookahead which checks for a digit in the string. Basically, .* matches the whole string and then backtracks 1 by 1 to match a digit. If it matches a digit, the regex engine comes back to its position before match. So, it just checks for a pattern.

{7,} is a quantifier which matches previous pattern 7 to many times

^ is the beginning of a string

edited Jun 1, 2013 at 21:50

PointedEars

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answered Jun 1, 2013 at 18:55

Anirudha

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2 Comments

Ro Yo Mi Over a year ago

I like this solution... simple and elegant.

dirty sanchez Over a year ago

@Anirudh Thank you very much, this looks so simple :)

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