尝试使用 nsIPrefBranch 在 Firefox 扩展上存储数据会出现 NS_ERROR_UNEXPECTED
我正在尝试在 Firefox 扩展中保存少量持久数据。
因此，我尝试像这样使用 nsIPrefBranch：
var db = Components.classes["@mozilla.org/preferences-service;1"].getService(Components.interfaces.nsIPrefBranch);
if(db.getCharPref('epoch')){ ///do something.. }
但它似乎不起作用，并且出现此错误：
“组件返回失败代码：0x8000ffff (NS_ERROR_UNEXPECTED) [nsIPrefBranch.getCharPref]"
有人可以告诉我我做错了什么吗？
I'm trying to save a small amount of persistent data in a Firefox extension.
So, I'm trying to use nsIPrefBranch like this:
var db = Components.classes["@mozilla.org/preferences-service;1"].getService(Components.interfaces.nsIPrefBranch);
if(db.getCharPref('epoch')){ ///do something.. }
but it doesn't seem to work and I'm getting this error:
"Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED)
[nsIPrefBranch.getCharPref]"
Can somebody please tell what I'm doing wrong?
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不存在称为“纪元”的偏好 - 这就是此消息告诉您的内容。您必须先设置此首选项，然后
getCharPref()才能成功。这就是为什么扩展通常将对 nsIPrefBranch 的调用包装到 try .. catch 块中 - 错误是预料之中的。另一方面：首选项是一个共享空间（请在
about:config下查看它们）。您应该明确某个首选项属于您的扩展程序，并确保它不会与其他扩展程序或浏览器的首选项发生冲突。换句话说，使用“extensions.myExtension.epoch”之类的内容而不是“epoch”。There is no preference called "epoch" - that's what this message is telling you. You have to set this preference before you can expect
getCharPref()to succeed. Which is why extensions usually wrap calls tonsIPrefBranchintotry .. catchblocks - errors are expected.On a different note: preferences are a shared space (have a look at them under
about:config). You should make clear that a preference belongs to your extension and make sure it won't conflict with preferences of other extensions or the browser. In other words, use something like "extensions.myExtension.epoch" rather than "epoch".