encodeRFC5987ValueChars

encodeRFC5987ValueChars.js

// Posted at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/encodeURIComponent
var fileName = 'my file(2).txt';
var header = "Content-Disposition: attachment; filename*=UTF-8''" + encodeRFC5987ValueChars(fileName);

console.log(header); 
// logs "Content-Disposition: attachment; filename*=UTF-8''my%20file%282%29.txt"


function encodeRFC5987ValueChars (str) {
    return encodeURIComponent(str).
        // Note that although RFC3986 reserves "!", RFC5987 does not,
        // so we do not need to escape it
        replace(/['()]/g, escape). // i.e., %27 %28 %29
        replace(/\*/g, '%2A').
            // The following are not required for percent-encoding per RFC5987, 
            //  so we can allow for a little better readability over the wire: |`^
            replace(/%(?:7C|60|5E)/g, unescape);
}

encodeRFC5987ValueChars.php

function encodeRFC5987ValueChars ($str) {
	// See http://tools.ietf.org/html/rfc5987#section-3.2.1
	// For better readability within headers, add back the characters escaped by rawurlencode but still allowable
	// Although RFC3986 reserves "!" (%21), RFC5987 does not
	return preg_replace_callback('@%(2[1346B]|5E|60|7C)@', function ($matches) { // !#$&+^`| are the characters matched here, respectively
		return chr('0x' . $matches[1]);
	}, rawurlencode($str));
}