为什么此JSON字符串无法解析? [英] Why does this JSON string fail to parse?

问题描述

也许我暂时看不到它，但是为什么这个JSON字符串无法解析?应该是有效的.

Maybe I just don't see it at the moment, but why does this JSON string fail to parse? It should be valid.

var content = $.parseJSON('{"foobar" : "hallo\"tow"}');

工作示例: http://jsfiddle.net/w6yjpame/2/

推荐答案

由于要以字符串文字形式创建JSON，因此需要转义\本身:

Because you're creating that JSON in a string literal, you need to escape the \ itself:

var content = $.parseJSON('{"foobar" : "hallo\\"tow"}');

console.log(content);

---

说明:

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Explanation:

在JSON中，"个字符使用\个字符进行转义.这使得以下完全有效的JSON:

In JSON, " characters are escaped using \ characters. That makes the following perfectly valid JSON:

{"foobar" : "hallo\"tow"}

现在，在您的示例中，您正在JavaScript字符串中构造此JSON值:

Now, in your example, you were constructing this JSON value within a JavaScript string:

'{"foobar" : "hallo\"tow"}'

由于JavaScript字符串也转义"字符和\字符，因此引入了一个微妙的问题.即，以下字符串文字:

This introduces a subtle issue, due to the fact that JavaScript strings also escape " characters with \ characters. That is, the following string literal:

'\"'

...保留值:

"

现在，将其再次应用于您的示例，我们发现该字符串文字:

Now, applying that to your example again, we find that this string literal:

'{"foobar" : "hallo\"tow"}'

...实际上拥有值:

... actually holds the value:

{"foobar" : "hallo"tow"}

如您所见，我们丢失了\.幸运的是，这很容易解决，因为\字符也可以用JavaScript字符串中的\字符转义，这就是我的解决方案.所以，现在，修改后的字符串文字:

As you can see, we've lost our \. Fortunately, this is easy to work around, as \ characters can also be escaped with \ characters in JavaScript strings, which is what my solution does. So now, the revised string literal:

'{"foobar" : "hallo\\"tow"}'

被解析为包含预期值的字符串:

gets parsed as a string holding the intended value:

{"foobar" : "hallo\"tow"}

...然后可以将其解析为格式正确的JSON.

... which can then be parsed as properly formatted JSON.

从textarea读取时或由于ajax请求而没有此问题的原因是JSON值不是由字符串文字定义的.仅由于字符串文字语法而需要额外的\，并且争夺谁先抢占"引号的竞争正在进行(嗯，这并不是真正的竞争……字符串文字总是会获胜).

The reason you don't have this issue when reading from a textarea or as the result of an ajax request is that the JSON value isn't being defined by a string literal. The extra \ is only required due to string literal syntax, and the competition going on for who's going to escape the " quote first (well, not really a competition... the string literal always wins).

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