带有reviver函数的JSON.parse返回未定义 [英] JSON.parse with reviver function returns undefined

问题描述

我是JSON新手，并且在 JSON.parse() :

I am new to JSON and getting this exception while using reviver parameter in JSON.parse():

TypeError: Cannot read property 'name' of undefined(…).

没有reviver参数代码可以正常工作，但是使用reviver参数时，它将引发上述异常.为什么会这样?

Without reviver parameter code works fine but with reviver parameter it throws the above exception. Why is that happening ?

var str = ' { ' +
    ' "name" : "Username", ' +
    ' "fname" : "Fathername" '
+ ' } ';

var jObj = JSON.parse(str, function (a, b) {
  console.log(a + "=>" + b);
});

document.write(
  "<h1>" + jObj.name + "</h1>",
  "<h2>" + jObj.fname + "</h2>"
);

推荐答案

因为您的reviver函数隐式返回undefined.

Because your reviver function returns implicitly undefined.

您必须返回一些内容，即变量b:

You have to return something, i.e. the variable b:

var str = JSON.stringify({ name: 'Username', fname: 'Fathername' });

var jObj = JSON.parse(str, function (a, b) {
  console.log(a, '=>', b);
  return b;
});

document.write('<h1>' + jObj.name + '</h1>', '<h2>' + jObj.fname + '</h2>');

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