1.计算系统当前是星期几

菜鸟：
var str = "";
var week = new Date().getDay();
if (week === 0) {
str = "今天是星期日";
} else if (week === 1) {
str = "今天是星期一";
} else if (week === 2) {
str = "今天是星期二";
} else if (week === 3) {
str = "今天是星期三";
} else if (week === 4) {
str = "今天是星期四";
} else if (week === 5) {
str = "今天是星期五";
} else if (week === 6) {
str = "今天是星期六";
}

中层：
var a = ["日", "一", "二", "三", "四", "五", "六"];
var week = new Date().getDay();
var str = "今天是星期" + a[week];
console.log(str);

高手：
var str = "今天是星期" + "日一二三四五六".charAt(new Date().getDay());

2.数组对象某一属性映射
菜鸟：

var a1 =[{
id: "0001",
placeCode: 'sh',
value: 0.5
},{
id: "0002",
placeCode: 'sz',
value: 1.5
},{
id: "0003",
placeCode: 'sh',
value: 2.5
}];

    var newValue;
    var a2 = $.map(a1, function(obj,key){
        if (obj.placeCode == "sh") {
            newValue = "沪";
        } else  if (obj.placeCode == "sz"){
            newValue = "深";
        }
        return ($.extend(obj,{value:newValue}));
    });

中层：
var maps= new Map([['sh','沪'],['sz','深']]);
var a2 = $.map(a1, function(obj,key){
obj.placeCode = maps.get(obj.placeCode);
return obj;
});

高手：
var toStr = {
sh : '沪',
sz : '深'
};
var a2 = $.map(a1, function(obj,key){
var placeCode = obj.placeCode;
obj.placeCode = toStr[placeCode] ? toStr[placeCode] : placeCode;
return obj;
});