RegEx For Alphanumeric Characters But Not Only Numeric

I need a RegEx in JavaScript for an HTML form to do the following matches: Abc123 - Accepted Abc - Accepted 123 - Not Accepted Am I doing something wrong ?? if(eventName == '

Solution 1:

You can use this regex expression

^(?![0-9]*$)[a-zA-Z0-9]+$

This expression has a negative lookahead to ensure that the string does not contain numbers only.

Check the demo here:

Demo

Given your code after edit, if you want to check if the given string matches your regex, you can do something like this:

Demo

Solution 2:

You can use this regex to make sure at least one alphabet is there:

/^\w*?[a-zA-Z]\w*$/

RegEx Demo

RegEx Breakup:

^         # start
\w*?      # Match 0 or more word characters (non-greedy)
[a-zA-Z]  # Match an English alphabet 
\w*       # Match 0 or more word characters
$         # end

Solution 3:

You could use a lookahead to check if an alphabetic character is present or not.

Regex: ^(?=.*[A-Za-z])\w+$

Explanation:

• (?=.*[A-Za-z]) This looks ahead if there is an alphabet anywhere in the string. If yes then it matches the next part of regex.

Output

• Not Matched: 123 _123 123_

• Matched: a_123 a12_3 asd as_j a_

Regex101 Demo

Solution 4:

I'm not exactly sure what do you want to archive, but I guess that you can use a simple regex like

^([0-9])*[a-zA-Z]+[a-zA-Z0-9]*$

Match something that doesn't start with digits, and starts with letters (upper or lowercase) one or more times, and then match alphanumeric zero or more times.

http://regexr.com/3d2gl

Regarding the code you provided, you need to use the opposite logic. eventName.match(/^(?![0-9]*$)[a-zA-Z0-9]+$/) will return true if matches, ie, if the username is valid. So you need to change it to something like

(...)
else if( ! eventName.match(/^(?![0-9]*$)[a-zA-Z0-9]+$/) )
{
    // Invalid username
    errorCount++;
    document.getElementById('error1').innerHTML="Please Enter a Valid Name";
}
(...)

or

(...)
else if( eventName.match(/^(?![0-9]*$)[a-zA-Z0-9]+$/) )
{
    // Username is valid, do your logic here.
}
(...)