script.js

// ==UserScript==
// @name             Simple Yahoo
// @namespace        http://www.example.com/
// @description      -
// @include          http://www.yahoo.co.jp/*
// ==/UserScript==
// https://gist.github.com/1107277
var load,execute,loadAndExecute;load=function(a,b,c){var d;d=document.createElement("script"),d.setAttribute("src",a),b!=null&&d.addEventListener("load",b),c!=null&&d.addEventListener("error",c),document.body.appendChild(d);return d},execute=function(a){var b,c;typeof a=="function"?b="("+a+")();":b=a,c=document.createElement("script"),c.textContent=b,document.body.appendChild(c);return c},loadAndExecute=function(a,b){return load(a,function(){return execute(b)})};

loadAndExecute("//ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js", function() {
  $("body").html($("#searchbox"));
});