I would like to know that since objects on JavaScript work as references, how I still to get the properties values from a cloned object as shown below:
let user = {
name: 'Dan',
age: 26,
sayHi(){
console.log('Hi', this.name);
}
}
let user2 = user;
user.name = 'Suzan';
user = null;
console.log(user2.name);
//return SuzanIf object user received null, user2 shouldn't be null as well? Since they are pointing to the same memory addresses?
After you do
user2 = user;
both variables are pointing to the same object. But when you do
user = null;
you just change where user is pointing, that has no effect on where user2 is pointing. It still points to the original object.
If you're familiar with languages like C, it's analogous to this:
struct u {
char *name;
int age;
};
struct u foo = {"Dan", 26};
struct u *user = &foo;
struct u *user2 = user;
user->name = "Suzan";
user = NULL;
printf("%s\n", user2->name);
Changing one pointer doesn't affect another pointer that points to the same memory.
user2 = {...user}
obj = {...obj} copy behavior.Don't think about this in terms of memory addresses. JavaScript doesn't deal with computing at that level.
let user = {}
The value of user is a reference to an object.
let user2 = user;
Note the value of user2 is a reference to the same object.
user.name = 'Suzan';
Now the name property of that object has the value 'Suzan'.
This gives exactly the same result as using user2.name in the same way.
user = null;
Now the value of user is null.
The value of user2 is still a reference to that object.
Assigning null to user only changes the value of user. It doesn't affect the object that it's old value was a reference to.
console.log(user2.name);
Since user2 is a reference to the original object, this still works.
If you also assigned user2 = null then there would be no references to that object left and you would be unable to access it (and it would get garbage collected).
When you make a reference of an object, the referenced object will only change the property not the shape of object(user2).
If you do change user object to null or empty array, user2 will always stay same.
user2is a reference to the same object asuser.user = null;doesn't causeuser2 = nullas well.