A few tips on JavaScript namespaces

Recently, refactoring things, encounter namespace Settings, search some knowledge, consult some masters, write down their own experience
I'm sure you all know that window is top-level, so I'm not going to write window here, so I'm going to ignore it

1: about the top level

var ns = ns || {};

As you can see, if the Object is not found, it automatically creates a new Object(); If so, use the object directly so that it is not overwritten.
2: the second level Of course, you can also create a second level under the top-level ns, namely

ns.ModuleClass = {};

As you can see, a class is created under ns, and of course you can continue to create methods in the class, which is this:

ns.ModuleClass.method1= function() {////};

3: multistage So what do I do, like this com.qw.view, I want to set it to a namespace, so I'm going to set the namespace for each of the separated names, for each of the objects

Let's look at an example of setting it under window:

function namespace(sSpace) {
  var arr = sSpace.split('.'),i = 0,nameI;
  var root = window;
  for (; nameI = arr[i++];) {
    if (!root[nameI]) {
      root[nameI] = {};
    }
    root = root[nameI];
  }
  return root;
}

And you can see that this is really the idea that I talked about above, which is to use a traversal, to set all the separated objects as objects, so that each separated object can be used separately.

4. Make a list of commonly used ones , a quick and easy way to set up a namespace

if (!window.ns) { 
  window.ns = {};
} 
var ns; 
if(typeof ns == "undefined"){ 
  ns = {}; 
} 
if(typeof ns.ClassName == "undefined"){
  ns.ClassName = {};
}