JSON.parse Reviver函数是否具有n + 1个键? [英] JSON.parse reviver function has n+1 keys?
问题描述
我想测试代码重载，可以在解析JSON字符串时提供reaviver函数.
因此，此代码:
JSON.parse('{"p": 5}', function(k, v) { if (k === "") return v; return v * 2; }).p;
产量10(确定).
但是后来我问自己:这是什么?让我们删除它！:
But then I asked myself, 'what is this if (k === "") thing?' Lets remove it!:
JSON.parse('{"p": 5}', function(k, v) { return v*2;}).p; //undefined !!
也许因为5是整数?让我们尝试parseInt:
Maybe because 5 is an integer? Let's try with parseInt:
JSON.parse('{"p": 5}', function(k, v) { return parseInt(v)*2;}).p; //undefined !!
很奇怪...
所以我想看看是哪个键(尽管这里只有一个)引起了麻烦:
So then I wanted to see which keys (although there is only one here) are causing the trouble:
JSON.parse('{"p": 5}', function(k, v) { alert(v)}).p;
有2条警报:
-
5
[object Object]
IMHO k和v用于key和value，实际上这里只有一个键.
IMHO k and v are for key and value, and indeed there is only one key here.
这是什么?而且为什么，我必须检查if (k === "")吗?
What is this other alert? And why do I have to check if (k === "")?
推荐答案
答案在您提供的链接中...
The answer is in the link you provided...
最终，将使用空字符串和最高值调用reviver，以允许转换最高值.
The reviver is ultimately called with the empty string and the topmost value to permit transformation of the topmost value.
在k === ""
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