Convert Google Spreadsheet gid to wid and vice versa (Base 36)

google-spreadsheet-id-converter.js

/**
 * Base 36 convert Google Worksheet Id (wid)
 * to Google Spreadsheet ID (gid)
 * 
 * @param  string wid [example: `od6` is equal sheet `0`]
 * @return string     [gid]
 */
function wid2gid(wid) {
 return parseInt(String(wid), 36)^31578;
}

/**
 * Base 36 convert Google Spreadsheet ID (gid)
 * to Google Worksheet Id (wid)
 * 
 * @param  string gid [extract from url `gid=ID`]
 * @return string     [wid]
 */
function gid2wid(gid) {
 return parseInt((gid^31578)).toString(36);
}