SOURCE

<script>
    //函数声明
    function square(number){
        return number*number;
    }
    console.log(square(3));

    //函数表达式(匿名)
    var square = function(number){return number*number}
    var x = square(3);  //9

    //Function构造器
    var x = new Function("a","b","return a*b");

</script>