基础类型有哪些?复杂类型有哪些?有什么特征?##
如下代码的输出? 为什么?##
var obj1 = {a:1, b:2};
var obj2 = {a:1, b:2};
console.log(obj1 == obj2);//false,二者指向的两块堆内存
console.log(obj1 = obj2);//使obj1指向obj2的堆内存
console.log(obj1 == obj2);//true,二者指向同一块堆内存
写一个函数getIntv,获取从当前时间到指定日期的间隔时间##
function getIntv(str){
var val = Date.parse(str) - Date.now();
var dd = Math.floor(val/(24*60*60*1000));
var hh = Math.floor((val-(dd*24*60*60*1000))/(60*60*1000));
var mm = Math.floor((val-(dd*24*60*60*1000+hh*60*60*1000))/(60*1000));
var ss = Math.floor((val-(dd*24*60*60*1000+hh*60*60*1000+mm*60*1000))/1000);
var time = "据除夕还有 "+dd+" 天 "+hh+" 小时 "+mm+" 分 "+ss+" 秒"
return time;
}
var str = getIntv("2017-01-07");
console.log(str)//据除夕还有 172 天 16 小时 9 分 43 秒
把数字日期改成中文日期##
function getChsDate(str){
var date = new Date(str);
var year = date.getFullYear().toString(),
month = date.getMonth(),
day = date.getDate();
var arr=["零","一","二","三","四","五","六","七","八","九","十","十一","十二","十三","十四","十五","十六","十七","十八","十九","二十","二十一","二十二","二十三","二十四","二十五","二十六","二十七","二十八","二十九","三十","三十一"];
var chsYear = "";
for (var i = 0; i < year.length; i++) {
chsYear += arr[year[i]];
}
chsDate = chsYear+"年"+arr[month + 1]+"月"+arr[day]+"日";
return chsDate
}
var str = getChsDate('2016-07-18');
console.log(str); // 二零一六年七月十八日
写一个函数获取n天前的日期##
function getLastNDays(val){
var lastNDays = new Date(Date.now() - val*24*60*60*1000);
var str = lastNDays.getFullYear()+"-"+(lastNDays.getMonth()+1)+"-"+lastNDays.getDate();
return str;
}
var lastWeek = getLastNDays(7); // "2016-7-11"
var lastMonth = getLastNDays(30); // "2016-6-18"
获取执行时间##
var Runtime = (function(){
var startDate,endDate;
return {
start: function(){
startDate = Date.now();
},
end: function(){
endDate = Date.now();
},
get: function(){
return endDate - startDate;
}
};
}());
Runtime.start();
//todo something
Runtime.end();
console.log( Runtime.get() );
楼梯有200级,每次走1级或是2级,从底走到顶一共有多少种走法?用代码(递归)实现##
function fn(n){
if (n===1) {
return 1;
}
if (n===2) {
return 2;
}
return fn(n-1) + fn(n-2);
}
写一个json对象深拷贝的方法,json对象可以多层嵌套,值可以是字符串、数字、布尔、json对象中的任意项##
function objCopy(obj){
var newObj = {};
for (var key in obj) {
if(typeof arr[key] === "object"){
newObj[key] = objCopy(obj[key])
}else{
newObj[key] = obj[key];
}
}
return newObj;
}