Hi,

first of all: i have absolutely no experience with regular expressions, and just a little bit with java script. :-|

The Task: I have a HTML form (name "Sensors") where a special sensor ID has to be entered : <INPUT type="text" size="40" maxlength="16" name="Sensor1_ID" value=""/>

I need to check the content of the text field with following rules:

- The Sensor-ID must have 16 characters

- Only HEX values are allowed (0-9 a-f A-F)

- The last two characters (position 15+16) must be "10" or "28".

What i currently have:

Following JavaScript checks (OnSumbit) the content of the text field:

function CheckSensor () {
    if (document.Sensors.Sensor1_ID.value.length != 16) {
      alert("Invalid ID!")
      document.Sensors.Sensor1_ID.focus();
      return false;
    }
}

What i need:

Add a regular expression for condition 2 and 3.

 Thank you in advance!

Try this: 

if(document.Sensors.Sensor1_ID.value.match(/^[a-f\d]{14}(?:10|28)$/i)) {
  // valid
} else {
  // invalid
}

A (short) explanation: 

^                 -   the beginning of the string
[a-f\d]{14}   -   followed by 14 numerical values or the characters 'a', 'b', 'c', 'd', 'e' or 'f'
(?:10|28)     -   followed by either '10' or '28'
$                 -   followed by the end of the string