Di in the Angularjs

Di in the Angularjs
Always thought angular in the di is very tall things, also wrote a di demo, know that the difficulty is the last dynamic code execution: I now know the value of the parameter, but also know the method I want to execute/create the object's class, then in the case that the number of arguments is dynamic, How can I execute this method or create a new object? In my demo, I chose to use Eval.
But when I see the following statement in the ANGULARJS source code:

1 Switch(Self?-1: Args.length) {2          Case0:returnfn ();3          Case1:returnFN (args[0]);4          Case2:returnFN (Args[0], args[1]);5          Case3:returnFN (Args[0], args[1], args[2]);6          Case4:returnFN (Args[0], args[1], args[2], args[3]);7          Case5:returnFN (Args[0], args[1], args[2], args[3], args[4]);8          Case6:returnFN (Args[0], args[1], args[2], args[3], args[4], args[5]);9          Case7:returnFN (Args[0], args[1], args[2], args[3], args[4], args[5], args[6]);Ten          Case8:returnFN (Args[0], args[1], args[2], args[3], args[4], args[5], args[6], args[7]); One          Case9:returnFN (Args[0], args[1], args[2], args[3], args[4], args[5], args[6], args[7], args[8]); A          Case10:returnFN (Args[0], args[1], args[2], args[3], args[4], args[5], args[6], args[7], args[8], args[9]); -         default:returnfn.apply (self, args); -}

A moment of intoxication. Angularjs unexpectedly enumerates 11 kinds of cases, then chooses the corresponding situation according to the parameter number. I think it's the stupidest and the stupidest way. But I don't think it's going to be more experienced than Google's guys, so there's got to be a reason. Check out the information found:
1. In strict mode, Eval doesn't work.
2. Both fn.apply () and Fn.call () are slower than FN ()
So my Getbean method in the Di of JavaScript should read:

1     //Core Approach2di.getbean=function(beanname) {3         //look at the cache, and some words go directly back4         if(beans[beanname]!=undefined)5             returnBeans[beanname];6Console.log ("haha" +beanname);7         varfn= This. Config[beanname];8         if(fn==undefined)return;9         varargs=getarguments (FN);Ten         if(!args) args=[]; One         varargss=NewArray (); A         varObjstr= ""; -         varIndex=0; -         varobj; the          for(varIinchargs) { -argss[i]=(Di.getbean (args[i])); -objstr+= "argss[" +index+ "],"; -index++; +         } -Objstr=objstr.substring (0, Objstr.length-1); +Objstr= "Obj=new (FN) (" +objstr+ "); "; A         /*The whole method can be implemented by this eval method, at it takes a string parameter and compiles and executes the contents of the string according to the Javasript standard. - The most important thing is that the variables inside the eval also follow JavaScript's function scope: that is, variables can be defined outside of Eval .*/ -         Switch(args.length) { -              Case0:obj=NewFN (); Break; -              Case1:obj=NewFN (Argss[0]); Break; -              Case2:obj=NewFN (argss[0],argss[1]); Break; in              Case3:obj=NewFN (argss[0],argss[1],argss[2]); Break; -             default: toeval (OBJSTR); Break; +         } -beans[beanname]=obj; the         returnobj; *};

Di in the Angularjs