The difference between the JS class reference method

Mode 1:

function A (b) {this.parter = b;}  function B () {}function Test () {var b = new B (); New A (b);

Mode 2:

function A () {this.parter = null;}  function B () {}function Test () {var a = new A (); A.parter = new B ();}

The two biggest differences are:

In the first way, a carefree access to the B attribute, B is definitely present.

In the second way, access to the B property does not necessarily exist.

The reason is that the assignment statement is executed only after the a instantiation is complete in the second way.

This article is from the "Technology Life" blog, please be sure to keep this source http://wangyuelucky.blog.51cto.com/1011508/1686624

The difference between the JS class reference method