An object-merged function throws an error

I have a need to combine an object with a second object, and if the second object has a property of the first object, the value of the two object will prevail.

Just beginning to feel like this is a very simple function, it's written like this:

/** * Merges the object src into DES, encounters the same attribute as the Des attribute, and notes that the attribute is also deep copy * @param des target Object * @param src object to be merged */function Merge2object (DES,SRC) {    if (typeof (DES)! = "Object" | | typeof (SRC)! = "Object") {        throw new TypeError ();    }    For (var prop in Src) {        if (Des.hasownproperty (prop))            continue;        else            Des[prop] = Src[prop];    }}

The result later encountered some errors, after the investigation, found that this function is really a slag: I forgot that if value is another object, the value corresponding to a key of the SRC object will be referenced in the past. This can cause SRC to be modified by some obscure place. So this function needs to be changed:

function Merge2object (des,src) {    if (typeof (DES) = "Object" | | typeof (SRC)! = "Object") {        throw new TypeError ();    } For    (var prop in Src) {        if (Des.hasownproperty (prop))            continue;        else        //des[prop] = Src[prop];            Des[prop] = Deepclone (Src[prop]);}    }

　　

/*** deep Copy an object * @param obj to deep copy the object */function deepclone (obj) {   if (typeof (obj)! = "Object" | | obj = = NULL)//Use = = to cover null and Undefined     return obj;  When obj is an object,   var re_obj = {};   for (var key in obj) {     Re_obj[key] = Deepclone (Obj[key]);//Recursion down  }return re_obj;}

It seems to be careful to write something later.

An object-merged function throws an error