JS冒号的作用

1.声明对象的成员
var Book =
{
Name: '法',
Price: 100,
Discount : function(rate)
{
this.Price *= rate;
}
};
alert(Book.Price);
Book.Discount(0.8); // 8折
alert(Book.Price);

2.switch语句分支
var a = 2;
switch (a)
{
case 0:
alert('0');
break;
case 1:
alert('1');
break;
case 2:
alert('2');
break;
default:
alert('_');
}

3.三元表达式
var a = 2;
var b = 4;
var k = (a > b ? 1 : 2);