javascript get system mac address

1<?php
2  
3// PHP code to get the MAC address of Client
4$MAC = exec('getmac');
5  
6// Storing 'getmac' value in $MAC
7$MAC = strtok($MAC, ' ');
8  
9// Updating $MAC value using strtok function, 
10// strtok is used to split the string into tokens
11// split character of strtok is defined as a space
12// because getmac returns transport name after
13// MAC address   
14echo "MAC address of client is: $MAC";
15?>