javascript基础教程之表达式和构造函数详解

var functionName = function([arg1 [,arg2 [...,argn]]]){
    statement;
}
var functionName = function funcName([arg1 [,arg2 [...,argn]]]){
    statement;
}

var tensquared = (function(x) {return x*x;}(10));

var test = function fn(){
   return fn;
}
console.log(test);//fn(){return fn;}
console.log(test());//fn(){return fn;}
console.log(test()());//fn(){return fn;}

var test = function fn(){   
  return fn === test;
}
console.log(test());//true
console.log(test === fn);//ReferenceError: fn is not defined

//IE11-浏览器无效，均输出undefined
//chrome在处理匿名函数的name属性时有问题，会显示函数表达式的名字
function fn(){};
console.log(fn.name);//'fn'
var fn = function(){};
console.log(fn.name);//''，在chrome浏览器中会显示'fn'
var fn = function abc(){};
console.log(fn.name);//'abc'

var functionName = new Function(['arg1' [,'arg2' [...,'argn']]],'statement;');

var sum = new Function('num1','num2','return num1 + num2');
//等价于
var sum = function(num1,num2){    
  return num1+num2;
}

var test = 0;
function fn(){
    var test = 1;
    return new Function('return test');
}
console.log(fn()());//0

var o = new Math.min();//Uncaught TypeError: Math.min is not a constructor