前端文章汇总

https://www.jianshu.com/p/82fa0c99e019

1、时间字符串相减得出天数

   // 时间字符串相减
    function dateMinus(date1, date2) {
        //date1:小日期   date2:大日期
        var sdate = new Date(date1);
        var now = new Date(date2);
        var days = now.getTime() - sdate.getTime();
        var day = parseInt(days / (1000 * 60 * 60 * 24));
        return day;
    }

2、多选框如何充当单选框使用?（jquery支持）

 // 设置单选框
            $("input:checkbox").click(function () {
                var boxArray = document.getElementsByName(this.name);
                for (var i = 0; i <= boxArray.length - 1; i++) {
                    if (boxArray[i] == this && this.checked) {
                        boxArray[i].checked = true;
                    } else {
                        boxArray[i].checked = false;
                    }
                }
            });

3、获取当前时间【格式一：年月日，格式二：年月日-时分秒】

//获取当前日期，格式YYYY-MM-DD
    function getNowFormatDay() {
        var char = "-";
        var nowDate = new Date();
        var day = nowDate.getDate();
        var month = nowDate.getMonth() + 1;//注意月份需要+1
        var year = nowDate.getFullYear();
        //补全0，并拼接
        return year + char + completeDate(month) + char + completeDate(day);
    }

    //获取当前时间，格式YYYY-MM-DD HH:mm:ss
    function getNowFormatTime() {
        var nowDate = new Date();
        var colon = ":";
        var h = nowDate.getHours();
        var m = nowDate.getMinutes();
        var s = nowDate.getSeconds();
        //补全0，并拼接
        return getNowFormatDay(nowDate) + " " + completeDate(h) + colon + completeDate(m) + colon + completeDate(s);
    }

    //补全0
    function completeDate(value) {
        return value < 10 ? "0" + value : value;
    }

4、半年后日期

// 半年后
    function getNowFormatDay2() {
        var char = "-";
        var nowDate = new Date();

        nowDate.setMonth(nowDate.getMonth() + 6); //加半年
        var day = nowDate.getDate();
        var month = nowDate.getMonth() + 1;//注意月份需要+1
        var year = nowDate.getFullYear();
        //补全0，并拼接
        return year + char + completeDate(month) + char + completeDate(day);
    }

5、月末

 /**
     * 判断是否为当月的最后一天
     */
    function isLastDayOfMonth() {
        var flag = new Boolean(false);
        var date = new Date();

        var year = date.getFullYear();
        var month2 = date.getMonth()+1;
        var month = date.getMonth()+1;
        var today = date.getDate();

        var new_year = year; //取当前的年份
        var new_month = month++;//取下一个月的第一天，方便计算（最后一天不固定）
        if(month>12){//如果当前大于12月，则年份转到下一年
            new_month -=12; //月份减
            new_year++; //年份增
        }
        var new_date = new Date(new_year,new_month,1); //取当年当月中的第一天

        var month_last_day = (new Date(new_date.getTime()-1000*60*60*24)).getDate();

        // 当前时间
        var resultTime1 =year+"-"+month2+"-"+today;
        // 月底时间
        var resultTime2 = new_year+"-"+new_month+"-"+month_last_day;
        if(resultTime1 == resultTime2){
            flag = true;
        }
        return flag;
    }

6、下月第一天 和 下月最后一天

    /*获取下个月的第一天*/
    function nextMonthFirstDay() {
        var time = new Date();
        var year = time.getFullYear();
        var month = time.getMonth() + 2;
        if (month > 12) {
            month = month - 12;
            year = year + 1;
        }
        var day = 1;

        return year + '-' + completeDate(month) + '-' + completeDate(day);
    }

    /*获取下个月的最后一天*/
    function nextMonthLastDay() {
        var time = new Date();
        var year = time.getFullYear();
        var month = time.getMonth() + 2;
        if (month > 12) {
            month = month - 12;
            year = year + 1;
        }
        var day = this.nextMonthDay(year, month);
        return year + '-' + completeDate(month) + '-' + completeDate(day);
    }


    function nextMonthDay(year, month) {//判断每月多少天
        var day31 = [1, 3, 5, 7, 8, 10, 12];
        var day30 = [4, 6, 9, 11];
        if (day31.indexOf(month) > -1) {
            return 31;
        } else if (day30.indexOf(month) > -1) {
            return 30;
        } else {
            if (this.isLeapYear(year)) {
                return 29;
            } else {
                return 28;
            }
        }
    }

    function isLeapYear(year) {//判断是否为闰年
        return (year % 4 == 0) && (year % 100 != 0 || year % 400 == 0);
    }

    //补全0
    function completeDate(value) {
        return value < 10 ? "0" + value : value;
    }