JS Shallow copy (address reference) and deep copy (clone)

Shallow copies and deep copies are relative to reference types.

JS has two major types of value types (basic data types) and reference types (Object,function,array);

Value types are saved on the stack, and reference types are saved on the heap.

A shallow copy is simply the address of a copy object.

//shallow copy of ObjectvarAA = {name: ' AA ', age:26, DX: {dxname: ' Dxname ', dxage:24 } };varBB =Aa
Console.log (BB===AA); //true //here represents the same address pointed to  Console.log (bb        . name); //AABb.name= ' BB ';        Console.log (Aa.name); //BBConsole.log (Bb.name);//BB

The object is saved above the heap, and the AA variable simply saves the address of the AA object 6ff65a1c;

Bb=aa just give the address 6ff65a1c to BB, so point to the same object, so changed the Bb.name,aa.name also followed the change.

A deep copy is a copy of the object completely.

varA = {name: ' AA ', age:26, DX: {dxname: ' Dxname ', dxage:24 } }; varb =NewObject (); B.name=A.name; B.age=A.age; B.DX= {};//open up a space and then copyB.dx.dxname=A.dx.dxname; B.dx.dxage=A.dx.dxage; B.name= ' BB '; B.dx.dxage= 30; Console.log (A===b); Console.log (A);                                                       Console.log (a); Console.log (' B ');                                                       Console.log (b); 

Because B is getting a copy of a, so change B will not affect the A

varDeepcopy =function(source) {//Deep copy function    varresult = {};  for(varKeyinchsource) {                                                                           //recursively copies the value of type object, regardless of the function typeResult[key] =typeof(Source[key]) = = = ' object '?deepcopy (Source[key]): Source[key]; }                                                                                              returnresult; }                                                                                              

varA = {name: ' AA ', age:26, DX: {dxname: ' Dxname ', dxage:24 } }; /*var b = new Object ();                                                      B.name = A.name;                                                        B.age = A.age;                B.DX = {};                                              Open up a space and then copy the B.dx.dxname=a.dx.dxname; B.dx.dxage=a.dx.dxage;*/                                              varb=Deepcopy (a); B.name= ' BB '; B.dx.dxage= 30; Console.log (A===b); Console.log (A);                                                       Console.log (a); Console.log (' B ');                                                       Console.log (b); 

Shallow and deep copies of arrays

//Array Shallow copyvararr = ["One", "one", "three"]; varArrto =arr; arrto[1] = "Test"; Document.writeln ("Original value of the array:" + arr + "<br/>");//Export: Original value of array: One,test,threeDocument.writeln ("New value of the array:" + Arrto + "<br/>");//Export: New value for array: One,test,three                                                                                 //Array Deep CopyvarARR2 = ["One", "one", "one", "three"]; varArrtoo = Arr.slice (0); arrtoo[1] = "Set Map"; Document.writeln ("Original value of the array:" + arr2 + "<br/>");//Export: Original value of array: One,two,threeDocument.writeln ("New value of the array:" + Arrtoo + "<br/>");//Export: New value for array: One,set map,three

JS Shallow copy (address reference) and deep copy (clone)