js 变量转换成 json

// 定义一个JavaScript对象
let person = {
    name: "张三",
    age: 30,
    isStudent: false,
    courses: ["数学", "英语"],
    address: {
        city: "北京",
        street: "朝阳路"
    }
};

// 将对象转换为JSON字符串
let jsonString = JSON.stringify(person);

console.log(jsonString);

{"name":"张三","age":30,"isStudent":false,"courses":["数学","英语"],"address":{"city":"北京","street":"朝阳路"}}

function stringifyWithCircularReference(obj) {
    const seen = new WeakSet();
    return JSON.stringify(obj, (key, value) => {
        if (typeof value === 'object' && value !== null) {
            if (seen.has(value)) {
                return '[Circular]';
            }
            seen.add(value);
        }
        return value;
    });
}

let circularObj = {};
circularObj.self = circularObj;

let jsonString = stringifyWithCircularReference(circularObj);
console.log(jsonString); // 输出: {"self":"[Circular]"}

let objWithFunc = {
    name: "张三",
    sayHello: function() {
        console.log("Hello!");
    },
    age: undefined
};

function replacer(key, value) {
    if (typeof value === 'function') {
        return value.toString();
    }
    if (value === undefined) {
        return null; // 或者其他默认值
    }
    return value;
}

let jsonString = JSON.stringify(objWithFunc, replacer);
console.log(jsonString); // 输出: {"name":"张三","sayHello":"function() { console.log(\"Hello!\"); }","age":null}