@require this script and you'll get $URL.encode(str) and $URL.decode(str) available.

$URL.encode(str) returns encodeURIComponent(str) but in encoding=document.characterSet
$URL.decode(str) returns decodeURIComponent(str) but in encoding=document.characterSet
$URL.encodeBuffer(str) returns an Uint8Array containing all encoded byte data in encoding=document.characterSet
$URL[encoding].encode/decode/encodeBuffer to call encode/decode/encodeBuffer in specific encoding.

for now, only big5 and gbk are supported for $URL.encode(str). $URL.decode(str) supports all encodings that your browser supports.

License: MIT
Modified from: https://github.com/EtherDream/str2gbk/