I have written a function, which efficiently results in the expected behaviour, without use of any libraries or frameworks. A dynamic demo can be found at this fiddle: http://jsfiddle.net/w8D2G/1/
Documentation
Definitions:
The shown example values will be used at the Usage section, below
- Haystack - The string to search in (default = query string. e.g: ?size=small,medium)
- Needle - The key to search for. Example: size
- Value - The value to replace/add. Example: medium.
Usage (Example: input > output):
qs_replace(needle, value)
If value exists, remove: ?size=small,medium > ?size=small
If value not exists, add: ?size=small > size=small,mediumqs_replace(needle, options) Object options. Recognised options:
find
String. Returns true if the value exists, false otherwise.add, remove or toggle
String. Add/remove the given value to/from needle. If remove is used, and the value was the only value, needle is also removed. A value won't be added if it already exists.ignorecase
Ignore case while looking for the search terms (needle, add, remove or find).separator
Specify a separator to separate values of needle. Default to comma (,).
Note : A different value for String haystack can also be defined, by adding it as a first argument: qs_replace(haystack, needle, value) or qs_replace(haystack, needle, options)
Code (examples at bottom). Fiddle: http://jsfiddle.net/w8D2G/1/:
function qs_replace(haystack, needle, options) {
if(!haystack || !needle) return ""; // Without a haystack or needle.. Bye
else if(typeof needle == "object") {
options = needle;
needle = haystack;
haystack = location.search;
} else if(typeof options == "undefined") {
options = needle;
needle = haystack;
haystack = location.search;
}
if(typeof options == "string" && options != "") {
options = {remove: options};
var toggle = true;
} else if(typeof options != "object" || options === null) {
return haystack;
} else {
var toggle = !!options.toggle;
if (toggle) {
options.remove = options.toggle;
options.toggle = void 0;
}
}
var find = options.find,
add = options.add,
remove = options.remove || options.del, //declare remove
sep = options.sep || options.separator || ",", //Commas, by default
flags = (options.ignorecase ? "i" :"");
needle = encodeURIComponent(needle); //URL-encoding
var pattern = regexp_special_chars(needle);
pattern = "([?&])(" + pattern + ")(=|&|$)([^&]*)(&|$)";
pattern = new RegExp(pattern, flags);
var subquery_match = haystack.match(pattern);
var before = /\?/.test(haystack) ? "&" : "?"; //Use ? if not existent, otherwise &
var re_sep = regexp_special_chars(sep);
if (!add || find) { //add is not defined, or find is used
var original_remove = remove;
if (subquery_match) {
remove = encodeURIComponent(remove);
remove = regexp_special_chars(remove);
remove = "(^|" + re_sep + ")(" + remove + ")(" + re_sep + "|$)";
remove = new RegExp(remove, flags);
var fail = subquery_match[4].match(remove);
} else {
var fail = false;
}
if (!add && !fail && toggle) add = original_remove;
}
if(find) return !!subquery_match || fail;
if (add) { //add is a string, defined previously
add = encodeURIComponent(add);
if(subquery_match) {
var re_add = regexp_special_chars(add);
re_add = "(^|" + re_sep + ")(" + re_add + ")(?=" + re_sep + "|$)";
re_add = new RegExp(re_add, flags);
if (subquery_match && re_add.test(subquery_match[4])) {
return haystack;
}
if (subquery_match[3] != "=") {
subquery_match = "$1$2=" + add + "$4$5";
} else {
subquery_match = "$1$2=$4" + sep + add + "$5";
}
return haystack.replace(pattern, subquery_match);
} else {
return haystack + before + needle + "=" + add;
}
} else if(subquery_match){ // Remove part. We can only remove if a needle exist
if(subquery_match[3] != "="){
return haystack;
} else {
return haystack.replace(pattern, function(match, prefix, key, separator, value, trailing_sep){
// The whole match, example: &foo=bar,doo
// will be replaced by the return value of this function
var newValue = value.replace(remove, function(m, pre, bye, post){
return pre == sep && post == sep ? sep : pre == "?" ? "?" : "";
});
if(newValue) { //If the value has any content
return prefix + key + separator + newValue + trailing_sep;
} else {
return prefix == "?" ? "?" : trailing_sep; //No value, also remove needle
}
}); //End of haystack.replace
} //End of else if
} else {
return haystack;
}
// Convert string to RegExp-safe string
function regexp_special_chars(s){
return s.replace(/([[^$.|?*+(){}\\])/g, '\\$1');
}
}
Examples (Fiddle: http://jsfiddle.net/w8D2G/1/):
qs_replace('color', 'red'); //Toggle color=red
qs_replace('size', {add: 'medium'}); //Add `medium` if not exist to size
var starting_url = 'http://example.com?color=red&size=small,medium,large&shape=round'
starting_url = qs_replace(starting_url, 'color', 'red'); //Toggle red, thus remove
starting_url = qs_replace(starting_url, 'color', 'red'); //Toggle red, so add it
alert(starting_url);
