js中将对象转换为json

let obj = {
    name: "张三",
    age: 30,
    hobbies: ["篮球", "游泳"]
};

let jsonString = JSON.stringify(obj);
console.log(jsonString); // 输出: {"name":"张三","age":30,"hobbies":["篮球","游泳"]}

// 使用replacer函数
let replacer = (key, value) => {
    if (typeof value === "string") {
        return undefined; // 忽略字符串类型的值
    }
    return value;
};
let jsonStringWithReplacer = JSON.stringify(obj, replacer);
console.log(jsonStringWithReplacer); // 输出: {"age":30,"hobbies":[]}

// 使用space参数美化输出
let jsonStringWithSpace = JSON.stringify(obj, null, 2);
console.log(jsonStringWithSpace);
/*
输出:
{
  "name": "张三",
  "age": 30,
  "hobbies": [
    "篮球",
    "游泳"
  ]
}
*/

let seen = new WeakSet();
let replacer = (key, value) => {
    if (typeof value === "object" && value !== null) {
        if (seen.has(value)) {
            return '[Circular]'; // 或者返回其他标记值
        }
        seen.add(value);
    }
    return value;
};
let jsonString = JSON.stringify(obj, replacer);