Abhishek Gupta

The Sun won’t set at NIT Durgapur !

Regular Expressions in Javascript

Posted by abhiitechie on May 17, 2009

Here are some examples of using regular expressions for input validations in javascript.

var input = “hello222”;
var ok = false;

var dob_regex = /^([0-9]){2}(\/){1}([0-9]){2}(\/)([0-9]){4}$/;   // DD/MM/YYYY
var email_regex = /^[a-zA-Z0-9._-]+@([a-zA-Z0-9.-]+\.)+[a-zA-Z0-9.-]{2,4}$/;  // email address
var username_regex = /^[\w.-]+$/;  // allowed characters: any word . -, ( \w ) represents any word character (letters, digits, and the underscore _ ), equivalent to [a-zA-Z0-9_]
var num_regex = /^\d+$/; // numeric digits only
var search_regex = “/hello/”;
var password_regex = /^[A-Za-z\d]{6,8}$/;  // any upper/lowercase characters and digits, between 6 to 8 characters in total
var phone_regex = /^\(\d{3]\) \d{3}-\d{4}$/;  // (xxx) xxx-xxxx
var question_regex = /\?$/; // ends with a question mark

1. Check that there are at least 3 numeric characters in input
if ( input.match(/d/g) == null ) {
ok = false;
} else if ( input.match(/d/g).length < 3 )  {
ok = false;
} else {
ok = true;
}
2. Check that the input has a minimum of 8 characters
if ( input.length >= 8 ) {
ok = true;
}
3. Check that the input is in a correct date format (DD/MM/YYYY)
if ( dob_regex.test(input) ) {
ok = true;
}
4. Check that the input is in a correct email format (username@example.com)
if ( email_regex.test(input) ) {
ok = true;
}
5. Check that the input matches the specified username format
if ( username_regex.test(input) ) {
ok = true;
}
6. Check that the input contains only numeric characters
if ( input.match(num_regex) ) {
ok = true;
}
7. Search for a specific word in the input
if ( input.search(search_regex) != -1 ) {
ok = true;
}
8. Check that the input matches the specified password format
if ( input.match(password_regex) ) {
ok = true;
}
9. Check that the input matches the specified phone number format
if ( input.match(phone_regex) ) {
ok = true;
}
10. Check that the input is a question (ends with a question mark)
if ( question_regex.test(input) ) {
ok = true;
}

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6 Responses to “Regular Expressions in Javascript”

  1. […] See the original post here: Regular Expressions in Javascript « Abhishek Gupta […]

  2. good Regular Expressions, thank you very much for sharing? Can you sharing this Regular Expressions on my JavaScript site, http://javascriptbank.com/submit/ ?

    Thank

  3. Roger Roelofs said

    Great article. I appreciate the time it takes to to a write-up like this. The Email regex only covers the common cases. I can’t tell you how many times I’ve had to adjust the regex for validating email addresses.

  4. 허성훈의 생각…

    Regular Expressions in Javascript…

  5. Enlightened411 said

    Thanks Abhishek.

    [E] BTW, you have an error on this page —
    The above “abhiitechie” link is INVALID.

    Enlightened411
    (^_^)

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