js 获取时间 和推算时间日期的js

function getTheSpecifiedDate(date, num, type) {
  var a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z, result;
  r = new Date();
  date = date || (r.getFullYear() + ‘-‘ + (r.getMonth()+1) + ‘-‘ + r.getDate());
  num = num || 1;
  type = type || ‘d‘;
  if (num === 0) {
    return date;
  } 
  a = date.indexOf(‘ ‘) === -1 ? date : date.slice(0, date.indexOf(‘ ‘));
  b = date.indexOf(‘ ‘) === -1 ? ‘‘ : date.slice(date.indexOf(‘ ‘) + 1);
  if (/^\d{4}\/\d{1,2}\/\d{1,2}$/g.test(a)) {
    a = (a.split(‘/‘)).join(‘-‘);
    d = 0; 
  } else if (/^\d{1,2}\-\d{1,2}\-\d{4}$/g.test(a)) {
    a = a.split(‘-‘);
    a = a[2] + ‘-‘ + a[0] + ‘-‘ + a[1];
    d = 1; 
  } else if (/^\d{1,2}\/\d{1,2}\/\d{4}$/g.test(a)) {
    a = a.split(‘/‘);
    a = a[2] + ‘-‘ + a[0] + ‘-‘ + a[1];
    d = 2; 
  } else {
    d = 3; 
  }
  o = b.split(‘:‘).concat(); 
  c = b.split(‘:‘); 
  c[2] = typeof c[2] === ‘undefined‘ ? ‘00‘ : c[2];
  if (((+c[0] > 59) || (+c[0] < 0)) || ((+c[1] > 59) || (+c[1] < 0)) || ((+c[2] > 59) || (+c[2] < 0))) {
    console.log(‘日期非法‘);
    return date; 
  } else if (!(/((^((1[8-9]\d{2})|([2-9]\d{3}))([-\/\._])(10|12|0?[13578])([-\/\._])(3[01]|[12][0-9]|0?[1-9])$)|(^((1[8-9]\d{2})|([2-9]\d{3}))([-\/\._])(11|0?[469])([-\/\._])(30|[12][0-9]|0?[1-9])$)|(^((1[8-9]\d{2})|([2-9]\d{3}))([-\/\._])(0?2)([-\/\._])(2[0-8]|1[0-9]|0?[1-9])$)|(^([2468][048]00)([-\/\._])(0?2)([-\/\._])(29)$)|(^([3579][26]00)([-\/\._])(0?2)([-\/\._])(29)$)|(^([1][89][0][48])([-\/\._])(0?2)([-\/\._])(29)$)|(^([2-9][0-9][0][48])([-\/\._])(0?2)([-\/\._])(29)$)|(^([1][89][2468][048])([-\/\._])(0?2)([-\/\._])(29)$)|(^([2-9][0-9][2468][048])([-\/\._])(0?2)([-\/\._])(29)$)|(^([1][89][13579][26])([-\/\._])(0?2)([-\/\._])(29)$)|(^([2-9][0-9][13579][26])([-\/\._])(0?2)([-\/\._])(29)$))/ig.test(a))) {
    console.log(‘日期非法‘);
    return date; 
  }
  e = new Date(a + ‘ ‘ + b);
  f = parseInt(num); 
  if (type === ‘y‘) {
    g = e.getFullYear(); 
    g = g - f;
    h = e.getMonth() + 1; 
    i = e.getDate(); 
  } else if (type === ‘m‘) {
    g = e.getFullYear();
    h = e.getMonth() + 1; 
    if (f >= 0) {
      h = e.getMonth() + 1;
      m = parseInt(f / 12); 
      n = parseInt(f % 12); 
      m = n >= h ? m + 1 : m;
      if (n >= h) { 
        h = 12 - (n - h);
      } else {
        h = h - n;
      }
      g = g - m; 
    } else {
      f = Math.abs(f); 
      m = parseInt(f / 12); 
      n = parseInt(f % 12); 
      m = (n + h >= 12) ? m + 1 : m;
      if (h + n <= 12) { 
        h = h + n;
      } else {
        h = (h + n) % 12;
      }
      g = g + m; 
    }
    i = e.getDate(); 
  } else {
    if (type === ‘d‘) { 
      f = f * 24 * 60 * 60 * 1000;
    } else if (type === ‘h‘) { 
      f = f * 60 * 60 * 1000;
    } else if (type === ‘min‘) { 
      f = f * 60 * 1000;
    } else if (type === ‘s‘) { 
      f = f * 1000;
    }
    f = parseInt(f);
    e = new Date(Date.parse(e) - f);
    g = e.getFullYear(); 
    h = e.getMonth() + 1; 
    i = e.getDate(); 
  }
  if (g % 4 === 0 && /^(\d{4}\-2\-(30|31))|(\d{4}\-02\-(30|31))$/g.test(g + ‘-‘ + h + ‘-‘ + i)) { 
    i = ‘29‘;
  } else if (g % 4 !== 0 && /^(\d{4}\-2\-(29|30|31))|(\d{4}\-02\-(29|30|31))$/g.test(g + ‘-‘ + h + ‘-‘ + i)) {
    i = ‘28‘;
  } else if (/^(\d{4}\-(4|6|9|11)\-31)|(\d{4}\-(04|06|09|11)\-31)$/g.test(g + ‘-‘ + h + ‘-‘ + i)) {
    i = ‘30‘;
  }
  j = e.getHours() < 10 ? ‘0‘ + e.getHours() : e.getHours(); 
  k = e.getMinutes() < 10 ? ‘0‘ + e.getMinutes() : e.getMinutes(); 
  l = e.getSeconds() < 10 ? ‘0‘ + e.getSeconds() : e.getSeconds(); 
  switch (d) {
    case 0:
      if (!b) {
        return g + ‘/‘ + h + ‘/‘ + i;
      } else if (o.length === 2) {
        return g + ‘/‘ + h + ‘/‘ + i + ‘ ‘ + j + ‘:‘ + k;
      }
      return g + ‘/‘ + h + ‘/‘ + i + ‘ ‘ + j + ‘:‘ + k + ‘:‘ + l;
    case 1:
      if (!b) {
        return h + ‘-‘ + i + ‘-‘ + g;
      } else if (o.length === 2) {
        return h + ‘-‘ + i + ‘-‘ + g + ‘ ‘ + j + ‘:‘ + k;
      }
      return h + ‘-‘ + i + ‘-‘ + g + ‘ ‘ + j + ‘:‘ + k + ‘:‘ + l;
    case 2:
      if (!b) {
        return h + ‘/‘ + i + ‘/‘ + g;
      } else if (o.length === 2) {
        return h + ‘/‘ + i + ‘/‘ + g + ‘ ‘ + j + ‘:‘ + k;
      }
      return h + ‘/‘ + i + ‘/‘ + g + ‘ ‘ + j + ‘:‘ + k + ‘:‘ + l;
    case 3:
      if (!b) {
        return g + ‘-‘ + h + ‘-‘ + i;
      } else if (o.length === 2) {
        return g + ‘-‘ + h + ‘-‘ + i + ‘ ‘ + j + ‘:‘ + k;
      }
      return g + ‘-‘ + h + ‘-‘ + i + ‘ ‘ + j + ‘:‘ + k + ‘:‘ + l;
    default:
      return ‘请您传入 "yyyy-mm-dd hh:mm:ss"、 "yyyy/mm/dd hh:mm:ss"、 "yyyy-mm-dd hh:mm"、 "yyyy/mm/dd hh:mm"、"mm-dd-yyyy hh:mm:ss"、 "mm/dd/yyyy hh:mm:ss"、 "mm-dd-yyyy hh:mm"、 "mm-dd-yyyy hh:mm" 的日期格式‘;
  }
}
 
 function addByTransDate(dateParameter, num) {
var translateDate = "", dateString = "", monthString = "", dayString = "";
translateDate = dateParameter.replace("-", "/").replace("-", "/"); ;
var newDate = new Date(translateDate);
newDate = newDate.valueOf();
newDate = newDate - num * 24 * 60 * 60 * 1000; //备注 如果是往前计算日期则为减号 否则为加号
newDate = new Date(newDate);
//如果月份长度少于2，则前加 0 补位
if ((newDate.getMonth() + 1).toString().length == 1) {
monthString = 0 + "" + (newDate.getMonth() + 1).toString();
} else {
monthString = (newDate.getMonth() + 1).toString();
}
//如果天数长度少于2，则前加 0 补位
if (newDate.getDate().toString().length == 1) {
dayString = 0 + "" + newDate.getDate().toString();
} else {
dayString = newDate.getDate().toString();
}
dateString = newDate.getFullYear() + "-" + monthString + "-" + dayString;
return dateString;
}