function, new function, the difference between the new function

http://www.jb51.net/article/7955.htm

A function is a very important language element in JavaScript and provides a function keyword and a built-in object function, and the following are the possible uses and relationships between them.

Use method One:

var foo01 = function ()//or Fun01 = function ()
{
var temp = 100;
This.temp = 200;
return temp + this.temp;
}

Alert (typeof (FOO01));
Alert (foo01 ());
Run Result:
function
300 the most common function usage, set a JavaScript function. The two kinds of writing show the same effect, the only one is that the latter is a higher initialization priority. In a variable scope within a large expansion number, this refers to the owner of the Foo01, the Window object.

Use Method Two:

Var foo02 = new function ()   
 {  
      var temp = 100;  
     this.temp =  200; &NBSP
     return temp + this.temp;  
 } &NBSP

 alert (typeof (Foo02))   
 alert (Foo02.constructor ());    &NBSP
Run results:  object 
 300     This is a comparison of the use of puzzle function, as if to set a function. But this is actually a user-defined object in JavaScript, but this is an anonymous class. This usage has nothing to do with the use of the function itself, which constructs a variable scope in the large extension, this refers to the scope itself. &NBSP

     use method: 

var Foo3 = new Function (' var temp = This.temp =; return temp + this.temp; ');

Alert (typeof (Foo3));
Alert (Foo3 ());
Run Result: function
300 Use the System built-in function object to construct a function, which is identical to the first in method one in terms of both effect and initialization precedence, that is, the function body is given in string form.

Use method Four:

var Foo4 = Function (' var temp = This.temp =; return temp + this.temp; ');

Alert (typeof (Foo4));
Alert (Foo4 ());
Run Result:
function
300 This method is not commonly used, the effect and method of the same, but it is not clear that no new to generate any side effects, which also embodies the most features of javascript: flexible. Can save the province.

On the question of function initialization precedence, see the reply to "the difference between two implementations of the JS class definition prototype method."