From 33058f2b292b3a581333bdfb21b8f671898c5060 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:40:17 -0500 Subject: initial commit --- files/zh-cn/tools/debugger-api/index.html | 99 +++++++++++++++++++++++++++++++ 1 file changed, 99 insertions(+) create mode 100644 files/zh-cn/tools/debugger-api/index.html (limited to 'files/zh-cn/tools/debugger-api') diff --git a/files/zh-cn/tools/debugger-api/index.html b/files/zh-cn/tools/debugger-api/index.html new file mode 100644 index 0000000000..f7c20b6ebf --- /dev/null +++ b/files/zh-cn/tools/debugger-api/index.html @@ -0,0 +1,99 @@ +--- +title: Debugger-API +slug: Tools/Debugger-API +translation_of: Tools/Debugger-API +--- +
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Debugger 接口

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Mozilla 的JS引擎, SpiderMonkey, 提供了一个名为Debugger 的调试接口，开发者能够通过该接口使用JS代码观测和操纵另一端JS代码的运行. Firefox内置的开发者工具和 Firebug 插件都使用Debugger 来是实现它们的JavaScript调试器.同时，Debugger 也被广泛应用与实现其他类型的工具，例如tracers, coverage analysis, patch-and-continue等。

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Debugger 有三个基本的特点：

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In Gecko, the Debugger API is available to chrome code only. By design, it ought not to introduce security holes, so in principle it could be made available to content as well; but it is hard to justify the security risks of the additional attack surface.

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The Debugger API cannot currently observe self-hosted JavaScript. This is not inherent in the API’s design, but simply that the self-hosting infrastructure isn’t prepared for the kind of invasions the Debugger API can perform.

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Debugger 实例与影子对象

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Debugger reflects every aspect of the debuggee’s state as a JavaScript value—not just actual JavaScript values like objects and primitives, but also stack frames, environments, scripts, and compilation units, which are not normally accessible as objects in their own right.

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Here is a JavaScript program in the process of running a timer callback function:

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A running JavaScript program and its Debugger shadows +

A running JavaScript program and its Debugger shadows

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This diagram shows the various types of shadow objects that make up the Debugger API (which all follow some general conventions):

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The Debugger instance itself is not really a shadow of anything in the debuggee; rather, it maintains the set of global objects which are to be considered debuggees. A Debugger observes only execution taking place in the scope of these global objects. You can set functions to be called when new stack frames are pushed; when new code is loaded; and so on.

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Omitted from this picture are Debugger.Source instances, which represent JavaScript compilation units. A Debugger.Source can furnish a full copy of its source code, and explain how the code entered the system, whether via a call to eval, a <script> element, or otherwise. A Debugger.Script points to the Debugger.Source from which it is derived.

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Also omitted is the Debugger’s Debugger.Memory instance, which holds methods and accessors for observing the debuggee’s memory use.

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All these types follow some general conventions, which you should look through before drilling down into any particular type’s specification.

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All shadow objects are unique per Debugger and per referent. For a given Debugger, there is exactly one Debugger.Object that refers to a particular debuggee object; exactly one Debugger.Frame for a particular stack frame; and so on. Thus, a tool can store metadata about a shadow’s referent as a property on the shadow itself, and count on finding that metadata again if it comes across the same referent. And since shadows are per-Debugger, tools can do so without worrying about interfering with other tools that use their own Debugger instances.

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Examples

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Here are some things you can try out yourself that show off some of Debugger’s features:

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Gecko-specific features

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While the Debugger core API deals only with concepts common to any JavaScript implementation, it also includes some Gecko-specific features:

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Source Metadata

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