Javascript JSON.stringify not handling prototype correctly?

Question

I initialized my reuse classes like this (the constructor is usually a copy constructor):

function Foo() {}
Foo.prototype.a = "1";
Foo.prototype.b = "2";
Foo.prototype.c = [];
var obj = new Foo();
obj.c.push("3");

but JSON.stringify does not give the expected result:

JSON.stringify(obj);

{}

Variables work as expected for everything else.
If toJSON is overridden, it works fine:

Foo.prototype.toJSON = function () {
    return {
        a: this.a,
        b: this.b,
        c: this.c
    };
};
JSON.stringify(obj);

{"a": "1", "b": "2", "C": ["3"]}

It also works great if variables are defined inside the constructor:

function Alt() {
    this.a = 1;
    this.b = "2";
    this.c = [];
}
JSON.stringify(obj);

{"a": 1, "b": "2", "C": ["3"]}

What's happening?

+3

Mike emery Feb 12 '14 at 15:32

2 answers

JSON.stringify .

: , Stringify , .

: this.a ,

: ,

+1

michael truong 12 . '14 15:57

Pointy · Accepted Answer · 2014-02-12T15:53:46+0000

( ) :

function Constructor() { }
Constructor.prototype.a = "hello world";

var x = new Constructor();
alert(x.a); // "hello world"

"" :

alert(x.hasOwnProperty("a")); // false

JSON , . - , , : , , , JSON.parse() ( ).