foreword
Why are you writing this? Because it is encountered in the project, just record it.
How to distinguish between deep copy and shallow copy
To put it simply: Assuming that B copied A, when A/B is modified, see if A/B will change. If A/B also changes, it means a shallow copy. If A/B does not change, it is a deep copy. The origin of deep copy and shallow copy lies in the reference data type and memory address. (Here you need to understand the stack and data types )
Deep copy : A memory address is opened up in the A/B computer to store the copied object.
Shallow copy : It is a reference transfer rather than a value transfer, and A and B point to the same memory address.
How to change shallow copy to deep copy
1. The easiest way: first convert to a string, and then convert to an object; JSON.parse(JSON.stringify（））
2. Use recursion to copy all hierarchical attributes
Encountered scene
In vue: this.A = this.B; that is, B assigns A, and then I just want to change A; but, when I change A, B also changes; hahaha..., I used JSON.parse(JSON.stringify())