javascript 从 Greasemonkey 到 Page 访问变量，反之亦然

Accessing Variables from Greasemonkey to Page & vice versa

提问by cryptic ツ

I have the following code in test.jswhich is run right before </body>:

我在test.js 中有以下代码，它在 </body> 之前运行：

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

I have the following code in test.user.js:

我在test.user.js 中有以下代码：

(function () {

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

}());

'stovetop' gets alerted so I know the page javascript works, and document.titlegets changes so I know that the script javascript works. However, on the webpage I get the error:

'stovetop' 收到警报，所以我知道页面 javascript 有效，并document.title获得更改，因此我知道脚本 javascript 有效。但是，在网页上我收到错误消息：

Error: ReferenceError: greasy is not defined Source File: /test.js

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

How from the webpage do I access the variable set by Greasemonkey and how about vice versa?

我如何从网页访问由 Greasemonkey 设置的变量，反之亦然？

回答by Brock Adams

• Greasemonkey scripts operate in a separate scope and may also operate in a sandbox, depending on the @grantsettings.

• Additionally, the question code isolates greasyin a function scope (as gladoscc said).

• Finally, by default, test.jswill fire before the Greasemonkey script does, so it won't see any set variables, anyway. Use @run-at document-startto address that.

• 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设置。

• 此外，问题代码greasy在函数范围内隔离（如gladoscc 所说）。

• 最后，默认情况下，test.js将在 Greasemonkey 脚本执行之前触发，因此无论如何它都不会看到任何设置的变量。使用@run-at document-start来解决这个问题。

So, given this test.js, run right before </body>:

所以，给定这个test.js，在之前运行</body>：

window.targetPages_GlobalVar = 'stovetop';

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

Then the following will work:

然后以下将起作用：

No sandbox:

没有沙箱：

// ==UserScript==
// @name        _Greasemonkey and target page, variable interaction
// @include     http://YOUR_SERVER.COM/YOUR_PATH/*
// @include     http://output.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);

With sandbox, no function scope, unsafeWindow:
==> Important update:Greasemonkey changed unsafeWindow handling with version 2.0, the next sample script will not work with GM 2.0 or later. The other two solutions still work.

使用沙箱，没有函数作用域，unsafeWindow：
==>重要更新：Greasemonkey 在 2.0 版中更改了 unsafeWindow 处理，下一个示例脚本将不适用于 GM 2.0 或更高版本。其他两种解决方案仍然有效。

// ==UserScript==
// @name        _Greasemonkey and target page, variable interaction
// @include     http://YOUR_SERVER.COM/YOUR_PATH/*
// @include     http://output.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);

With sandbox, no function scope, Script Injection:

使用沙箱，没有函数作用域，脚本注入：

// ==UserScript==
// @name        _Greasemonkey and target page, variable interaction
// @include     http://YOUR_SERVER.COM/YOUR_PATH/*
// @include     http://output.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);
}

---

---

Notes:

笔记：

1. You can test these script against this page(output.jsbin.com/esikut/1).
2. With no sandbox, unsafeWindowand windoware the same.

3. All of these scripts produce the same output on the console:

   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
   

4. The Script Injectioncode will work in a variety of browsers besides Firefox. unsafeWindowcurrently only works in Firefox+Greasemonkey(or Scriptish) or Chrome+Tampermonkey.

1. 您可以针对此页面(output.jsbin.com/esikut/1)测试这些脚本。
2. 没有沙箱，unsafeWindow和window都是一样的。

3. 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
   

4. 该脚本注入代码将在各种除了Firefox浏览器的工作。unsafeWindow目前仅适用于 Firefox+Greasemonkey（或 Scriptish）或 Chrome+Tampermonkey。

回答by apscience

Your variable greasyis defined in the scope of the anonymous function. You cannot access greasyeven in your userscript, unless it is part of your function. Example:

您的变量greasy是在匿名函数的范围内定义的。您greasy甚至无法在您的用户脚本中访问，除非它是您的功能的一部分。例子：

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

Do it this way:

这样做：

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

Also, why are you putting all your code in an anonymous function and then executing it?

另外，为什么要将所有代码放在匿名函数中然后执行？

回答by Pikamander2

You can also use localStorage:

您还可以使用localStorage：

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

localStorage.getItem("numberOfThings");