Unique ID (alpha numeric)

getUID.php

<?php
/**
 * Unique ID alpha numeric (0-9a-z)
 *
 * @return 20 character alphanumeric unique id
 **/
function getUID($id=null) {
    $s = uniqid('', true);
    $hex = substr($s, 0, 13);
    $dec = $s[13] . substr($s, 15); // skip the dot
    $uid = base_convert($hex, 16, 36) .
        ($id ? base_convert($id, 10, 36) : '') .
        base_convert($dec, 10, 36);
    $slen = strlen($uid);

    if ($slen > 20)
        return substr($uid, 0, 20);
    
    // Pad from right to 20 chars
    for ($i=0; $i < 20 - $slen; $i++) {
        $uid .= base_convert(rand(0, 35), 10, 36);
    }
    return $uid;
}

uniqid.js

/**
 * Unique ID
 * 
 * @return string 32 character alphanumeric ID
 */
function uniqid() {
	var out = new Date().getTime().toString(36).split(""),
		outlen = out.length;
	
	for (var i = 0; i < 32 - outlen; i++)
		out.push(Math.floor(Math.random() * 36).toString(36));

	return out.join("");
}