validation format of javascript

Question

I found these javascript validation codes:

<script type="text/javascript">
function validasi_input(form){
   pola_username=/^[a-zA-Z0-9\_\-]{6,100}$/;
   if (!pola_username.test(form.username.value)){
      alert ('Username minimal 6 karakter dan hanya boleh Huruf atau Angka!');
      form.username.focus();
      return false;
   }
return (true);
}
</script>

I want to ask about this part:

pola_username=/^[a-zA-Z0-9\_\-]{6,100}$/;

does anyone can tell me how to understand this kind of format? is it format for letter, or number, or characters?

This called Regular Expression. You should search more about this keyword. — long.luc
– long.luc, Commented Jun 24, 2014 at 2:55

Ryan · Accepted Answer · 2014-06-24 03:00:55Z

1

/^[a-zA-Z0-9\_\-]{6,100}$/;

In english this means: that a string can have any letter either uppercase or lowercase, numbers, underscores, and hyphens. A minimum length of 6 characters, and a maximum length of 100.

Further details:

The string must start with either a letter, number, underscore, or hyphen.

edited Jun 24, 2014 at 3:00

answered Jun 24, 2014 at 2:55

Ryan

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1 Comment

Ryan Over a year ago

@user3740978 anytime I'm always here to help.

Tamil Selvan C · Accepted Answer · 2014-06-24 03:01:15Z

0

/^[a-zA-Z0-9\_\-]{6,100}$/

^ asserts that we are at the beginning of the string

[a-zA-Z0-9_-] string can have any letter either uppercase , lowercase, numbers, underscores, or hyphens.

{6,100} matches a length of character having from 6 to 100

$ asserts that we are at the end of the string

answered Jun 24, 2014 at 3:01

Tamil Selvan C

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Harpreet Singh · Accepted Answer · 2014-06-24 03:10:21Z

0

Various RegEx explanation/testing tools.

1. Explain RegEx

2. RegEx101

3. Debuggex Demo

^[a-zA-Z0-9\_\-]{6,100}$

Regular expression visualization

answered Jun 24, 2014 at 3:10

Harpreet Singh

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Community · Accepted Answer · 2020-06-20 09:12:55Z

0

^ is an anchor. It asserts position at start of the string

[a-zA-Z0-9\_\-]{6,100} match a single character present in the list below

{6, 100}: Between 6 and 100 times, as many times as possible, giving back as needed

a-z a single character in the range between a and z (case sensitive)

A-Z a single character in the range between A and Z (case sensitive)

0-9 a single character in the range between 0 and 9

\_ matches the character _ literally

\- matches the character - literally

$ is an anchor. It asserts position at end of the string.

An alternative regex using flags would be:

/^[a-z\d\_\-]{6,100}$/i

Here \d matches digits (0-9), and flag i denotes case insensitivity.

This is what regular expressions do to perform matches, for starters:

_{(source: gyazo.com)}

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Jun 24, 2014 at 3:02

Unihedron

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