JavaScript 嵌套尝试异常

JavaScript nested try exception

提问by Robert Rocha

I am reading up on JavaScript exceptions:

我正在阅读 JavaScript异常：

You can nest one or more try...catch statements. If an inner try...catch statement does not have a catch block, the enclosing try...catch statement's catch block is checked for a match.

您可以嵌套一个或多个 try...catch 语句。如果内部 try...catch 语句没有 catch 块，则会检查封闭的 try...catch 语句的 catch 块是否匹配。

I think I understood it correctly and wrote this test code as follows:

我想我理解正确，写了这个测试代码如下：

try {

    try {
        throw "error";
    }

} catch( e ) {

    console.log( e );

}

But got this error:

但是得到了这个错误：

Uncaught SyntaxError: Missing catch or finally after try

Uncaught SyntaxError: Missing catch or finally after try

I know it clearly says that I am missing a catch or finally but the JavaScript documentation says my code should be valid or am I misunderstanding?

我知道它清楚地表明我错过了一个问题或最后但 JavaScript 文档说我的代码应该是有效的还是我误解了？

回答by T.J. Crowder

The quoted text is quite misleading because it says "if an inner try..catch doesn't have a catch block" which doesn't make any sense. It should just be "if an inner trydoesn't have...".

引用的文本非常具有误导性，因为它说“如果内部 try..catch 没有 catch 块”，这没有任何意义。它应该只是“如果内部try没有......”。

In JavaScript, you can't just have a tryon its own; it hasto have a catch, finally, or both. So the scenario that quote is referring so isa try/catchcontaining a try/finally(not another try/catch):

在 JavaScript 中，您不能只拥有一个try；它有有一个catch，finally或两者兼而有之。所以引用所指的场景所以 isatry/catch包含一个try/finally（不是另一个try/catch）：

try {
    try {
        throw "error";
    }
    finally {
    }
} catch( e ) {
    console.log( e );
}

回答by Gaurav Kakkar

It is specified here: (https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Statements/try...catch)

它在此处指定：（https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Statements/try...catch）

The try statement consists of a try block, which contains one or more statements, and at least one catch clause or a finally clause, or both. That is, there are three forms of the try statement:

try 语句由包含一个或多个语句的 try 块和至少一个 catch 子句或 finally 子句或两者组成。也就是说，try语句有以下三种形式：