js之Math对象

        var num = Math.random()*;
        var num1 = Math.floor(num); // 向下取整
        var num2 = Math.ceil(num); // 向上取整
        document.write(num2+'-<br>');
        document.write(num1);
 
        // 1-10 随机数
        var a = Math.floor(Math.random()*+);
        console.log(a);
 
        function selectForm(min,max){
            var ta = max - min + ;
            return Math.floor(Math.random() * ta + min);
        }
        console.log(selectForm(,));
 
        var colors = ["red","gree","blue","yellow","black"];
        var color = colors[selectForm(,colors.length-)];
        console.log(color);