记录前端工作中用的一些常用的函数（一）

//时间戳转日期
function getLocalTime(nS) {
    var date = new Date(nS * 1000);
    var year = date.getFullYear();
    var month = date.getMonth() + 1;
    month = month > 9 ? month : ("0" + month);
    var day = date.getDate();
    day = day > 9 ? day : ("0" + day);
    return year + "-" + month + "-" + day;
}
/**
 * @param nS为秒参数,默认return的日期分隔符为"-",形如“2017-12-22"
 * @returns {string}
 */

//时间戳转时间字符串
function getLocalDateTime(nS, dateSplitChar, length) {
    var date = new Date(nS * 1000);
    var year = date.getFullYear();
    var month = date.getMonth() + 1;
    month = month > 9 ? month : ("0" + month);
    var day = date.getDate();
    day = day > 9 ? day : ("0" + day);
    var hour = date.getHours();
    hour = hour > 9 ? hour : ("0" + hour);
    var minutes = date.getMinutes();
    minutes = minutes > 9 ? minutes : ("0" + minutes);
    var seconds = date.getSeconds();
    seconds = seconds > 9 ? seconds : ("0" + seconds);
    var str = year + dateSplitChar + month + dateSplitChar + day + " " + hour + ":" + minutes + ":" + seconds;
    return str.substr(0, length);
}
/**
 * @param nS 时间戳秒参数
 * @param dateSplitChar  时间字符串中日期之间的分隔符
 * @param length  默认显示到秒，截取字符串长度
 * @returns {string} 
 */


//根据时间字符串计算时间戳,自适应字符串的长度,但不能自定义分隔符
function calcTimestamp(datestr) {
    var arr = datestr.split(" ");
    var date = arr[0];//日期
    var arr0 = date.split("-");
    var year = 2017, month = 0, day = 1;
    switch (arr0.length){
        case 0:break;
        case 1:year = arr0[0];break;
        case 2:year = arr0[0], month = arr0[1]-1;break;
        case 3:year = arr0[0], month = arr0[1]-1, day = arr0[2];break;
    }
    var hour = 0, minute = 0, second = 0;
    if(arr.length>1){
        var time = arr[1];
        var arr1 = time.split(":");
        switch (arr1.length){
            case 0: break;
            case 1: hour = arr1[0];break;//时
            case 2: hour = arr1[0], minute = arr1[1];break;//时、分
            case 3: hour = arr1[0], minute = arr1[1], second = arr1[2];break;//时、分、秒
        }
    }
    return Date.parse(new Date(year, month, day, hour, minute, second))/1000;
}    }/**
 * 不能自定义分隔符
 * @param datestr  形如“2017-12-22 12:46:23”的时间字符串
 * @returns {number} 单位为秒
 */