Copying Objects
There are two types of copy javascript perform shallow copy and deep copy.
- Shallow Copy - copied data still points to the orignal data and changes in copied data affects orignal data.
- Deep Copy - copied data does not point to the orignal data both have different references.
We can use === to compare if both point to the same reference or not.
Ways to copy
- Using assignment operator = (performs shallow copy)
When copyPerson.name is changed to 'sourav' person.name also changes, so any changes on the copyPerson will affect the person object.
- Copy array using spread operator ...
In this example you can see person === copyPerson prints false, so when we change copyPerson.name it does not affects the person.name.
But person.address === copyPerson.address prints true, means copyPerson holds same reference as the orignal object for the nested objects.
- Copy using JSON.parse() and JSON.stringify() (performs deep copy)
Changing the value of copyPerson does not change the person value, in this case copyPeron does not share any reference of the person object.
person === copyPerson prints false
person.address === copyPerson.address prints false