const tempObj = {
    prop1 : "value1",
    prop2 : "value2"
}

//-----Concatinating / Adding New Key Values to Object--------//
Object.assign(tempObj, 
{
    "prop123" : "value123",
    "prop456" : "value456"
},

{
    "prop888" : "value888",
    "prop090" : "value090"
}
)

//--------Cloning an Object---------------//
const clonedObject = Object.assign({}, tempObj)
clonedObject.prop1 = "newProperty"  //it does not affect the original object

console.log(tempObj);
//console.log(clonedObject, tempObj);

//Find more in https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign
//-----------------------------------------------------------//