159. Pass by value vs Pass by reference

var a = 5;
var b = a;

b++;

let obj = {
  a:'a', 
  b:'b', 
  c: {
    deep:'try and copy me'
    }
};
let clone = Object.assign({}, obj);
let clone2 = {...obj}

obj.c.deep = 'hahaha';
console.log(obj)
console.log(clone)
console.log(clone2)

clone: 복제

shallow clone

: only clone the first layer
that is the memory adress in this object but within this object there was another adress to another

deep clone

var a = 5;
var b = a;

b++;

let obj = {
  a:'a', 
  b:'b', 
  c: {
    deep:'try and copy me'
    }
};
let clone = Object.assign({}, obj);
let clone2 = {...obj}
let superClone = JSON.parse(JSON.stringify(obj) )

obj.c.deep = 'hahaha';
console.log(obj)
console.log(clone)
console.log(clone2)
console.log(superClone)

cf. JSON is out of this course.
stringify turns everything in here into a string.

deep clone can have some performance implications(성능저하).