Prompt URL parameters bookmarklet

prompt-url-params-bookmarklet.js

javascript: document.location.search = (function(param, value, location){
    search = location.search;
    if (search) {
        pattern = new RegExp('([\?&]?)'+param+'=([^\?&#]*)');
        clue = search.match(pattern);
        if (clue) {
            search = search.replace(pattern, '$1'+param+'='+value);
        } else {
            search += '&'+param+'='+value;
        }
    } else {
        search = '?'+param+'='+value;
    }
    return search;
})('key', prompt('value of key is:'), document.location);