JS中冒号的作用
1.声明对象的成员
2.switch语句分支
3.三元表达式


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);