那你的對象就要是{a:"1",b:"name"}，a的值是字符串類型"1"而不是數字1

 let a = { a: 1, b: "name" }
 let b = JSON.stringify(a, (key, val) => typeof val === 'number' ? "" + val : val)

let obj = {a:1,b:"name"},
    _obj = JSON.stringify(obj, (k,v) => { 
    if(typeof v === 'number') {
        v = '' + v;
    }
    return v; 
});

var o = { a: 1, b: "name" };
var s = JSON.stringify(o, function (k, v) {
    return typeof v === "number" ? v + "" : v;
});
console.log(s);    // {"a":"1","b":"name"}