Trouble Converting jQuery Script to Plugin -

i'm trying convert pretty simple script takes search results twitter , outputs unordered list. first time trying write plugin , doesn't seem firing code when call it. script iteself works fine, code i've written plugin:

(function($) {      $.fn.tweetget = function(options) {          var defaults = {              query: 'from:twitter&rpp=10',             url: 'http://search.twitter.com/search.json?callback=?&q='         };          var options = $.extend(defaults, options);          return this.each(function() {              // tweets user query             $.getjson(options.url + options.query, function(data) {                  var tweets = [];                  $.each(data.results, function(i, tweet) {                      tweets.push('<li>' + tweet.text.parseurl().parseusername().parsehashtag() + '</li>');                 });                  $('#target').append('<ul>' + tweets.join('') + '</ul>');             });              // parse tweets urls , convert links             string.prototype.parseurl = function() {                 return this.replace(/[a-za-z]+:\/\/[a-za-z0-9-_]+\.[a-za-z0-9-_:%&~\?\/.=]+/g, function(url) {                     return url.link(url);                 });             };              // parse tweets twitter usernames , convert links             string.prototype.parseusername = function() {                 return this.replace(/(?:^|\s)@[a-za-z0-9_.-]+\b/, function(user) {                     var username = user.replace("@","")                     return user.link("http://twitter.com/"+username);                 });             };              // parse tweets hashtags , convert links             string.prototype.parsehashtag = function() {                 return this.replace(/[#]+[a-za-z0-9-_]+/g, function(hash) {                     var hashtag = hash.replace("#","%23")                     return hash.link("http://search.twitter.com/search?q="+hashtag);                 });             };         });     }; })(jquery); 

the function being called with:

$('#target').tweetget({query: 'from:twitter&rpp:10'}); 

everything outside of return this.each(function() {}; working fine, nothing placed within firing or giving me errors. tutorials i've read seem use same basic format can't seem figure out i'm doing wrong...

here working version: http://jsfiddle.net/jaaulde/qk35d/3/

( function( global ) {     var string, $;      if( global.jquery )     {         string = global.string;         $ = window.jquery;          string.prototype = $.extend( string.prototype, {             // parse tweets urls , convert links             parseurl: function()             {                 return this.replace( /[a-za-z]+:\/\/[a-za-z0-9-_]+\.[a-za-z0-9-_:%&~\?\/.=]+/g, function( url )                 {                     return url.link( url );                 } );             },             // parse tweets twitter usernames , convert links             parseusername: function()             {                 return this.replace( /@[a-za-z0-9_.-]+\b/g, function( user )                 {                     return user.link( 'http://twitter.com/' + user.replace( '@', '' ) );                 } );             },             // parse tweets hashtags , convert links             parsehashtag: function()             {                 return this.replace( /[#]+[a-za-z0-9-_]+/g, function( hash )                 {                     return hash.link( 'http://search.twitter.com/search?q=' + hash.replace( '#', '%23' ) );                 } );             }         } );          $.fn.tweetget = function( options )         {             var defaults = {                 query: 'from:twitter&rpp=10',                 url: 'http://search.twitter.com/search.json?callback=?&q='             };              options = $.extend( defaults, options );              return this.each( function()             {                 var target = this;                 // tweets user query                 $.getjson( options.url + options.query, function( data )                 {                     var tweets = [];                      $.each( data.results, function( i, tweet )                     {                         tweets.push( '<li>' + tweet.text.parseurl().parseusername().parsehashtag() + '</li>' );                     } );                      $( target ).append( '<ul>' + tweets.join('') + '</ul>' );                 } );             } );         };     } }( window ) ); 

watch answer updates explain modifications.

edits:

1. removed modifications of string prototype out of plugin--they should not there not part of plugin code, , redefined on every call plugin.
2. removed #target selector within plugin targeted element rather using collection against plugin had been called (adjusted scope due getjson callback).
3. removed var declaration in front of options = $.extend( defaults, options ); unneeded , there risk of wiping had been passed plugin on execution.
4. as aside, fixed parseusername function stop adding space in front of usernames in username urls
5. used preferred syntax localizing code