JavaScript中（动态函数，匿名函数）函数

<script type="text/javascript">
//动态函数
var add = new Function("x,y","var sum; sum=x+y; return sum;");
var he = add(4,8);
alert("he="+he);//12

//动态函数详解
var a = "var sum;";
var b = "sum = x + y;";
var c = "return sum;";
var square = new Function ( "x", "y", a+b+c);
alert ( square (2,3));//5

/*在这里，我们定义了变量a，b，c，我们让a等于字符串var sum,让b等于字符串sum = x+y;让c = 字符串return sum;
这样，var square = new Function ("x","y","var sum ; sum = x+y;return sum;");
我们就可以写成var square = new Function ( "x", "y",a+b+c);
把一个字符串分成了若干个独立的字符串的优点就在于我们可以通过修改其中的某些字符串来随时改变函数的作用,就好像b = "sum = x -y;"动态改变函数体*/
b = "sum = x -y;";
var square = new Function ( " x", "y",a+b+c);
alert(square (2,3));//-1
</script>

<script type="text/javascript">
var add3 = function (a,b){//匿名函数的地址赋给add3
return a+b;
}
alert(add3(7,8));//15

function haha()
{
alert("haha run");
}
var xixi = haha;
//上述代码可以简写成下面的方式。
var xixi = function()
{
alert("haha run");
}
</script>