function URLEncode (clearString)

Equivalent à  urlencode($str) de php mais pour javascript

function URLEncode (clearString) {
var output = '';
var x = 0;
clearString = clearString.toString();
var regex = /(^[a-zA-Z0-9_.]*)/;
while (x < clearString.length) {
var match = regex.exec(clearString.substr(x));
if (match != null && match.length > 1 && match[1] != '') {
output += match[1];
x += match[1].length;
}
else {
if (clearString[x] == ' ') output += '+';
else {
var charCode = clearString.charCodeAt(x);
var hexVal = charCode.toString(16);
output += '%' + ( hexVal.length < 2 ? '0' : '' ) + hexVal.toUpperCase();
}
x++;
}
}
return output;
}

source :  http://cass-hacks.com/articles/code/js_url_encode_decode/