封装一个time.js库

在使用JS内置对象Date时,觉得颇多不便,便基于Date的一些方法来封装一个time.js的时间库;

本篇文章仅作学习和尝试封装的简单记录,其中也记录了封装过程中遇到的一些bug和调试/解决方法

 function time(...params) {
    //接受多个参数,把参数打包为数组
    if (!(this instanceof time)) {
        return new time(...params)
    }//如果当前对象不是time函数构造出来的,就new一个

    if(arguments.length>1){
        params[1] -= 1//月份
    }
    this.date = new Date(...params)   //自有属性
    
 }

 time.prototype = {//共有属性
    constructor: time,
//重载,传参  
    parts(attrs){//读取
        if(attrs===undefined){
            console.log(this.date)
            //output:当前的中国标准时间
            return{
                year: this.date.getFullYear(),
                month: this.date.getMonth()+1,
                //月份index从0开始,加一调成现实月份
                weekday: this.date.getDay(),
                day: this.date.getDate(),
                //Uncaught TypeError: Cannot read properties of undefined (reading 'getDate')
                //已解决,把date(日期)写成data(数据)
                hour: this.date.getHours(),//前面修改后这里报错了,后来发现是前面结尾漏了逗号
                minute: this.date.getMinutes(),
                second: this.date.getSeconds(),
                ms: this.date.getMilliseconds()
            } 
        }else{//设置
            const { year, month, weekday, day, hour, minute,second, ms} = attrs//传参
            // if(year){
            //     this.date.setFullYear(year)
            // }缩写如下
            year !== undefined && this.date.setFullYear(year)//存在且不为undefined后执行
            //0是假值,会判断为不存在;设为undefined会把排除范围缩小,放出0
            month !== undefined && this.date.setMonth(month - 1)
            weekday !== undefined && this.date.setDay(weekday)
            //Uncaught ReferenceError: weekday is not defined//在上面传参,已解决
            day !== undefined && this.date.setDate(day)
            hour !== undefined && this.date.setHours(hour)
            minute !== undefined && this.date.setMinutes(minute)
            second !== undefined && this.date.setSeconds(second)
            ms !== undefined && this.date.setMilliseconds(ms)
        }
    },
    add(n, unit) {//日期增加; 传入 数字+日期单位
        const valid ='year month day hour minute second ms'.split(' ').includes(unit)
        console.log(valid)
        console.log(unit)
        if(!valid){//“防御性”编程
            throw new Error('输入的单位错误? 我不认识'+unit)
        }
        const table ={//map
            ms: 1,
            second: 1000,
            minute: 1000*60,
            hour: 1000*60*60,
            day: 1000*60*60*24
         }
        if( unit === 'year'){
            this.date.setFullYear(this.date.getFullYear()+n)
        }else if(unit ==='month'){
            this.date.setMonth(this.date.getMonth()+n)
        }else{//加上对应的毫秒数
            this.date = new Date(this.date-0+table[unit]*n)
        }
    },
    isLeapYear() {//判断是否闰年
        const year = this.date.getFullYear()
        if(year%4===0){
            if(year%100===0){
                if(year%400===0){
                    return true
                }else {
                    return false
                }
            } else{
                return true//被4整除但不被100整除
            }
        }else {
            return false
        }
    },
    lastDayOdfMonth(){//判断是否是每月最后一天
        const {year, month,hour,minute,second,ms} =this.parts()
        return new time(year, month+1, 0,hour,minute,second,ms)
    },
    format(pattern){//格式化输出
        console.log(pattern)
        const {year, month, day, hour, minute, second} =this.parts()
        console.log(this.parts())
        // 支持的占位符有 yyyy MM dd HH mm ss
        return pattern.replace(/yyyy/g, year)
            .replace(/MM/g, padLeftZero(month))
            .replace(/dd/g, padLeftZero(day))
            .replace(/HH/g, padLeftZero(hour))
            .replace(/mm/g, padLeftZero(minute))
            .replace(/ss/g, padLeftZero(second))
    }
 }
function padLeftZero(n){
    return n > 10? ''+n: '0'+n
}




//使用
 const t1 = time('2020-02-1')//t1不是时间本身,是用来操作时间的api

//格式化输出
 console.log(t1.format('yyyy年MM月dd日 HH:mm'))

//写入
 t1.parts({
    year:2022,
    month:10,
    day:19
 })
 const {year, month, day} = t1.parts()
 console.log(year, month, day)

 //add
 t1.add(2,'month')
 console.log(t1.date.toLocaleString())
 t1.add(3, 'day')
console.log(t1.date.toLocaleString())
//TypeError: Cannot read properties of undefined (reading 'toLocaleString')
console.log(t1.format('yyyy年MM月dd日 HH:mm'))

//找本月最后一天
const t2 = time('2001-01-01')
console.log(t2.date.toLocaleString())
console.log(t2.lastDayOdfMonth().date.toLocaleDateString())