Function defined in several ways

Many forms function definition. Common are the following categories.

1. custom function (function name)

function fn(){};

2. function expressions (anonymous function)

var fun =function(){};

3. Use new Function ( 'n1', 'n2', 'n3', ........, 'function body')

var fun =new Function('a','b','c','console.log(a+b+c)');
fun(1,2,3);

　　　3.1Function must all format string

　　　The third way 3.2 low efficiency, so rarely used

4. Function All functions are instance objects, also belong to the object function

var fun =new Function('a','b','c','console.log(a+b+c)');
fun(1,2,3);
console.dir(fun);
console.log(f instanceof Object);

Therefore, the specific object which can be summarized as the relationship shown in FIG.

The same logic can be bypassed to the object constructor common property of the object inheritance ES5.