Question

我在 test.js 中有以下代码，它在＆lt; / body＆gt;之前运行：

alert('stovetop');
alert(greasy);

我在 test.user.js 中有以下代码：

(function () {

    'use strict';
    var greasy = 'greasy variable';
    document.title = 'greasy title';

}());

'炉灶'会收到警报，所以我知道页面javascript有效，document.title会有变化，所以我知道脚本javascript有效。但是，在网页上我收到错误：

错误：ReferenceError：greasy未定义源文件：/test.js

如何从网页访问Greasemonkey设置的变量，反之亦然？

Answer 1

Greasemonkey脚本在单独的范围内运行，也可能在沙箱中运行，具体取决于@grant settings。
此外，问题代码在函数范围内隔离greasy（正如gladoscc所说）。
最后，默认情况下， test.js 将在Greasemonkey脚本执行之前触发，因此无论如何都不会看到任何设置变量。使用@run-at document-start解决此问题。

因此，鉴于此 test.js ，请在</body>之前运行：

window.targetPages_GlobalVar = 'stovetop';

console.log ("On target page, local global: ", targetPages_GlobalVar);
console.log ("On target page, script global: ", gmScripts_GlobalVar);

然后以下内容将起作用：

没有沙箱：

// ==UserScript==
// @name        _Greasemonkey and target page, variable interaction
// @include     http://YOUR_SERVER.COM/YOUR_PATH/*
// @include     http://jsbin.com/esikut/*
// @run-at      document-start
// @grant       none
// ==/UserScript==

//--- For @grant none, could also use window. instead of unsafeWindow.
unsafeWindow.gmScripts_GlobalVar = 'greasy';

console.log ("In GM script, local global: ", unsafeWindow.targetPages_GlobalVar);
console.log ("In GM script, script global: ", gmScripts_GlobalVar);

window.addEventListener ("DOMContentLoaded", function() {
    console.log ("In GM script, local global, after ready: ", unsafeWindow.targetPages_GlobalVar);
}, false);

使用沙箱，没有功能范围，unsafeWindow：
==＆GT; 重要更新： Greasemonkey changed unsafeWindow handling with version 2.0, the next sample script will not work with GM 2.0 or later。其他两个解决方案仍然有效。

// ==UserScript==
// @name        _Greasemonkey and target page, variable interaction
// @include     http://YOUR_SERVER.COM/YOUR_PATH/*
// @include     http://jsbin.com/esikut/*
// @run-at      document-start
// @grant    GM_addStyle
// ==/UserScript==
/*- The @grant directive is needed to work around a design change
    introduced in GM 1.0.   It restores the sandbox.
*/

unsafeWindow.gmScripts_GlobalVar = 'greasy';

console.log ("In GM script, local global: ", unsafeWindow.targetPages_GlobalVar);
console.log ("In GM script, script global: ", unsafeWindow.gmScripts_GlobalVar);

window.addEventListener ("DOMContentLoaded", function() {
    console.log ("In GM script, local global, after ready: ", unsafeWindow.targetPages_GlobalVar);
}, false);

使用沙箱，没有功能范围，脚本注入：

// ==UserScript==
// @name        _Greasemonkey and target page, variable interaction
// @include     http://YOUR_SERVER.COM/YOUR_PATH/*
// @include     http://jsbin.com/esikut/*
// @run-at      document-start
// @grant       GM_addStyle
// ==/UserScript==
/*- The @grant directive is needed to work around a design change
    introduced in GM 1.0.   It restores the sandbox.
*/

function GM_main () {
    window.gmScripts_GlobalVar = 'greasy';

    console.log ("In GM script, local global: ", window.targetPages_GlobalVar);
    console.log ("In GM script, script global: ", window.gmScripts_GlobalVar);

    window.addEventListener ("DOMContentLoaded", function() {
        console.log ("In GM script, local global, after ready: ", window.targetPages_GlobalVar);
    }, false);
}

addJS_Node (null, null, GM_main);

function addJS_Node (text, s_URL, funcToRun, runOnLoad) {
    var D                                   = document;
    var scriptNode                          = D.createElement ('script');
    if (runOnLoad) {
        scriptNode.addEventListener ("load", runOnLoad, false);
    }
    scriptNode.type                         = "text/javascript";
    if (text)       scriptNode.textContent  = text;
    if (s_URL)      scriptNode.src          = s_URL;
    if (funcToRun)  scriptNode.textContent  = '(' + funcToRun.toString() + ')()';

    var targ = D.getElementsByTagName ('head')[0] || D.body || D.documentElement;
    targ.appendChild (scriptNode);
}

注意：

您可以针对this page (jsbin.com/esikut)。
如果没有沙箱，unsafeWindow和window都是相同的。

所有这些脚本在控制台上产生相同的输出：

In GM script, local global: undefined
In GM script, script global: greasy
On target page, local global: stovetop
On target page, script global: greasy
In GM script, local global, after ready: stovetop

除了Firefox之外，脚本注入代码可以在各种浏览器中使用。 unsafeWindow目前仅适用于Firefox + Greasemonkey（或Scriptish）或Chrome + Tampermonkey。

Answer 2

您的变量greasy在匿名函数的范围内定义。即使在您的用户脚本中也无法访问greasy，除非它是您的功能的一部分。例如：

(function(){
    var foo = 5;
    alert(foo);
}();
alert(foo); //ERROR, because foo is undefined outside of the function.

这样做：

var foo = 5;
(function(){
     alert(foo);
}();
alert(foo);

另外，为什么要将所有代码放在匿名函数中然后执行它？

Answer 3

您也可以使用localStorage：

localStorage.setItem("numberOfThings", "42");

localStorage.getItem("numberOfThings");

从Greasemonkey访问变量到Page＆amp;反之亦然

3 个答案: