JSFiddle - React, Tailwind, and code Playground

JavaScript

swapjson = function (j1, j2) {
    var temp = {};
    
    for (key in j1) {
        temp[key] = j1[key];
        delete(j1[key]);
    }
    for (key in j2) {
        j1[key] = j2[key];
        delete(j2[key]);
    }
    
    for (key in temp) {
        j2[key] = temp[key];
    }
    
}

var myjson1 = {
    'x': 1000,
    'y': 1000
};
var myjson2 = {
    'x': 2000,
    'y': -2000
};

swapjson(myjson1, myjson2);
console.log(myjson1);
console.log(myjson2);