js的常用公共方法

1. 截取地址栏里携带的参数

/**
 * 解析地址
 * @param url
 * @param name
 * @returns {string|null}
 */
export function getQueryString(url, name) {
  let reg = new RegExp('(^|&)' + name + '=([^&]*)(&|$)', 'i');
  let r = ('?' + url.split('?')[1]).substr(1).match(reg);
  if (r != null) return unescape(r[2]);
  return null;
}

具体使用：let token = getQueryString(window.location.href, 'token')

2. 时间转换工具

①

/**
 * 时间戳转换工具
 * @param timestamp 时间戳
 * @returns {string} yy-mm-dd
 */
export function formatDate(timestamp) {
    if (!timestamp) {
        return "";
    }
    let date = new Date(timestamp);
    let month = date.getMonth() + 1;
    let strDate = date.getDate();
    if (month >= 1 && month <= 9) {
        month = "0" + month;
    }
    if (strDate >= 0 && strDate <= 9) {
        strDate = "0" + strDate;
    }
    let dateStr = date.getFullYear() + '-' + month + '-' + strDate;
    return dateStr;
}

②

/**
 * 时间戳转换工具
 * @param timestamp 毫秒时间戳
 * @returns {string} yy-mm-dd-hh-mm-ss
 */
export function formatTime(timestamp) {
  if (!timestamp) {
    return "";
  }
  let date = new Date(timestamp);
  let year = date.getFullYear();
  let month = date.getMonth() + 1;
  if (month >= 1 && month <= 9) {
    month = "0" + month;
  }
  let strDate = date.getDate() < 10 ? "0" + date.getDate() : date.getDate();
  let hours = date.getHours() < 10 ? "0" + date.getHours() : date.getHours();
  let min = date.getMinutes() < 10 ? "0" + date.getMinutes() : date.getMinutes();
  let sec = date.getSeconds() < 10 ? "0" + date.getSeconds() : date.getSeconds();
  let dateStr = year + '-' + month + '-' + strDate + " " + hours + ':' + min + ':' + sec;
  return dateStr;
}

③

/**
 * 时间戳转换工具
 * @param timestamp 毫秒时间戳
 * @returns {string} yy-mm-dd-hh-mm-ss
 */
export function formatTime(timestamp) {
  if (!timestamp) {
    return "";
  }
  let date = new Date(timestamp);
  let month = date.getMonth() + 1;
  let strDate = date.getDate();
  if (month >= 1 && month <= 9) {
    month = "0" + month;
  }
  if (strDate >= 0 && strDate <= 9) {
    strDate = "0" + strDate;
  }
  let dateStr = date.getFullYear() + '-' + month + '-' + strDate +
    " " + (date.getHours() < 10 ? "0" + date.getHours() : date.getHours()) + ':' +
    (date.getMinutes() < 10 ? "0" + date.getMinutes() : date.getMinutes()) +
    ':' + (date.getSeconds() < 10 ? "0" + date.getSeconds() : date.getSeconds());
  return dateStr;
}

④

/**
 * 获取当前时间
 * @returns {string} yyyy-MM-dd格式
 */
export function newDate() {
    let date = new Date();
    let month = date.getMonth() + 1;
    let strDate = date.getDate();
    if (month >= 1 && month <= 9) {
        month = "0" + month;
    }
    if (strDate >= 0 && strDate <= 9) {
        strDate = "0" + strDate;
    }
    let dateStr = date.getFullYear() + '-' + month + '-' + strDate;
    return dateStr;
}

⑤

/**
 * n天前的时间
 * @param n 时间差
 * @returns {string} yyyy-MM-dd格式
 */
export function beforeDate(n) {
    let date = new Date().getTime();
    date = date - n * 24 * 60 * 60 * 1000;
    return formatDate(date);
}

⑥

Date.prototype.format = function (fmt) {
  var o = {
    "M+": this.getMonth() + 1, //月份
    "d+": this.getDate(), //日
    "h+": this.getHours(), //小时
    "m+": this.getMinutes(), //分
    "s+": this.getSeconds(), //秒
    "q+": Math.floor((this.getMonth() + 3) / 3), //季度
    "S": this.getMilliseconds() //毫秒
  };
  if (/(y+)/.test(fmt)) fmt = fmt.replace(RegExp.$1, (this.getFullYear() + "").substr(4 - RegExp.$1.length));
  for (var k in o)
    if (new RegExp("(" + k + ")").test(fmt)) fmt = fmt.replace(RegExp.$1, (RegExp.$1.length == 1) ? (o[k]) : (("00" + o[k]).substr(("" + o[k]).length)));
  return fmt;
}
export default Date

// 用法 const dd = new Date(date)

obj.visitstartdate = dd.format("yyyy-MM-dd")

var begin = new Date();

var end = new Date();

new Date(begin.setMonth((new Date().getMonth() - 1)));

var begintime = begin.format("yyyy-MM-dd");

var endtime = end.format("yyyy-MM-dd");

$('#txtBeginVisitTime').val(begintime);

$('#txtEndVisitTime').val(endtime);

3. 字符串的截取

/**
 * 字符串截取
 * @param str 字符串
 * @param n 截至字符的下标
 * @returns {*}
 */
export function subString(str, n) {
  if (!n) return str;
  let sign = str.length <= n ? '' : '...';
  return str.substring(0, n) + sign;
}