设置@grant值时，如何访问“窗口”（目标页面）对象？

Z时代
2024-01-10
分类：问答

假设我正在使用以下网页：

<html>
<body>
<span id="click">click me</span>
<script>
var hello = function() {
    alert('hello');
}
document.getElementById('click').addEventListener('click', function(e) {
    hello();
});
</script>
</body>
</html>

我的Greasemonkey脚本是：

// ==UserScript==
// @name        My Script
// @include     http://example.com/hello.html
// @version     1
// @grant       none
// ==/UserScript==
window.hello = function() {
    alert('goodbye');
}

在禁用Greasemonkey脚本的情况下，单击#click页面上的元素将显示“ hello”警报。启用脚本后，单击元素将显示“再见”警报。

很简单。hello网页中的功能已被Greasemonkey脚本中的功能替换。

现在，假设我要使用Greasemonkey API。当我将@grant值设置为’none’以外的有效值时（例如// @grant

GM_setClipboard）[这会导致Greasemonkey将脚本作为“内容脚本”运行，而不是像“

none”一样在页面范围内运行]，Greasemonkey脚本无法执行工作。

window.hello 不再定位页面上的正确对象。

更换window.hello用unsafeWindow.hello看起来像它的工作，而是下面的错误是在JS控制台抛出：

错误：拒绝访问对象的权限

在@grant GM_setClipboard设置为目标并替换hello页面上的原始功能后，如何重写Greasemonkey脚本？

系统信息：

Windows 7 64位

Firefox 32.0

Greasemonkey 2.2

回答：

当您设置任何@grant其他值时，Greasemonkey会激活其沙箱，而Greasemonkey2.0将彻底改变unsafeWindow处理。

现在，为了在目标页面范围内创建或覆盖变量，您必须从技术菜单中正确选择。例如：

To Read:

```
Target page sets:       var foo = "bar";
```
GM script can read: unsafeWindow.foo //– “bar”

```
Target page sets:       var obj = {A: 1};
```
GM script can read: unsafeWindow.obj //– Object { A: 1 }

这并不总是可能的。

To Call:

Target page sets:       function func () {console.log ('Hi');}

GM script can call: unsafeWindow.func() //– “Hi”

To Write/Set:

```
unsafeWindow.foo = "Apple";
```

```
var gmObject        = {X: "123"};
```
unsafeWindow.obj = cloneInto (gmObject, unsafeWindow);

function gmFunc () {
console.log ("Lorem ipsum");
//-- Can use GM_ functions in here! :)

}

unsafeWindow.func = exportFunction (gmFunc, unsafeWindow);

考虑以下HTML：

<button id="helloBtn">Say "Hello".</button>

而这个JavaScript：

var simpleGlobalVar = "A simple, global var in the page scope.";
var globalObject    = {Letter: "A", Number: 2};
function simpleFunction () {
    console.log ("The target page's simpleFunction was called.");
}
var sayHello = function() {
    console.log ('Hello.');
}
document.getElementById ('helloBtn').addEventListener ('click', function () {
    sayHello ();
} );

如果在该页面上安装并运行此Greasemonkey脚本：

// ==UserScript==
// @name     _Demonstrate accessing target-page variables with @grant values set
// @include  http://fiddle.jshell.net/sepwL7n6/*/show/
// @require  http://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js
// @grant    GM_addStyle
// ==/UserScript==
console.log ("*** Greasemonkey script start.");
$("body").append ('<div id="gmArea">Added by Greasemonkey:<p></p></div>');
$("#gmArea > p:first").append ('<button id="gmShow">Access select target-page variables and functions</button>');
$("#gmArea > p:first").append ('<button id="gmChange">Change javascript things in the target-page scope.</button>');
$("#gmShow").click ( function () {
    //-- Access things from the target-page scope:
    console.log ("----------------");
    console.log ("==> simpleGlobalVar is: ", unsafeWindow.simpleGlobalVar);
    console.log ("==> globalObject    is: ", unsafeWindow.globalObject);
    console.log ("==> Calling target's simpleFunction():");
    unsafeWindow.simpleFunction ();
    //-- WARNING! This next technique is not robust, but works in some cases.
    console.log ("==> Calling target's button's click().");
    unsafeWindow.document.getElementById ('helloBtn').click ();
} );
$("#gmChange").click ( function () {
    this.disabled = true;   //-- Can only click once.
    unsafeWindow.simpleGlobalVar    = "Simple var... Intercepted by GM!";
    unsafeWindow.globalObject       = cloneInto (gmObject, unsafeWindow);
    unsafeWindow.sayHello           = exportFunction (sayHello, unsafeWindow);
    console.log ("==> Target page objects were changed.");
} );
var gmMessageStr    = "Function... Intercepted by GM, but also can use GM_ functions!";
function sayHello () {
    sayHello.K      = (sayHello.K  ||  0) + 1;
    console.log (gmMessageStr);
    GM_addStyle ('body {background: ' + (sayHello.K % 2  ?  "lime"  :  "white") + ';}');
}
var gmObject        = {message: "Object overridden by GM."};