How to encode a query string so that it is the value of another query string in javascript?

Question

encodeURIComponent will work. (You may or may not want the leading ‘?’, depending on what the script is expecting.)

var c= 'd e'
var query= '?a=b&c='+encodeURIComponent(c);
var uri= 'http://www.example.com/script?query='+encodeURIComponent(query);
window.location= uri;

Takes me to:

http://www.example.com/script?query=%3Fa%3Db%26c%3Dd%2520e

When you hover over that it may appear once-decoded in the browser's status bar, but you will end up in the right place.

escape/unescape() is the wrong thing for encoding query parameters, it gets Unicode characters and pluses wrong. There is almost never a case where escape() is what you really need.

Native escape method does that. but also you can create a custom encoder like:

function encodeUriSegment(val) {
  return encodeUriQuery(val, true).
             replace(/%26/gi, '&').
             replace(/%3D/gi, '=').
             replace(/%2B/gi, '+');
}

this will replace keys used in query strings. further more you can apply it to any other custom encodings by adding needed key-values pairs.