JavaScript开发中常用的方法集

// 格式化日期类型,fmt格式可选择

function dateFormat(fmt, date) {

  let ret;

  let opt = {

    "Y+": date.getFullYear().toString(), // 年

    "M+": (date.getMonth() + 1).toString(), // 月

    "D+": date.getDate().toString(), // 日

    "h+": date.getHours().toString(), // 时

    "m+": date.getMinutes().toString(), // 分

    "s+": date.getSeconds().toString(), // 秒

    "ms+": date.getMilliseconds().toString() // 毫秒

  };

  for (let k in opt) {

    ret = new RegExp("(" + k + ")").exec(fmt);

    if (ret) {

      fmt = fmt.replace(ret[1], ret[1].length == 1 ? opt[k] : opt[k].padStart(ret[1].length, "0"));

    }

  }

  return fmt;

}

let date = new Date();

let fDate = dateFormat("YYYY-MM-DD hh:mm:ss.ms", new Date(date));

// 计算时分秒差值

function timeDiffer(beginTime, endTime) {

  let ret = {};

  let date = new Date();

  let sTime = Date.parse(dateFormat("YYYY/MM/DD", date) + " " + beginTime);

  if (beginTime >= endTime) {

    date.setDate(date.getDate() + 1);

  }

  let eTime = Date.parse(dateFormat("YYYY/MM/DD", date) + " " + endTime);

  let differ = eTime - sTime;

  let hour = Math.floor(differ / 1000 / 60 / 60);

  let minute = Math.floor(differ / 1000 / 60 - hour * 60);

  let second = Math.floor(differ / 1000 - hour * 60 * 60);

  ret = {

    differHour: hour,

    differMinute: minute,

    differSecond: second

  };

  return ret;

}

let { differHour, differMinute, differSecond } = timeDiffer(beginTime, endTime);

// 深拷贝，即复制并独立一份数据，操作不影响原数据

function deepCopy(obj) {

  if (typeof obj !== "object") {

    return obj;

  }

  let result = Array.isArray(obj) ? [] : {};

  for (let i in obj) {

    if (obj.hasOwnProperty(i)) {

      if (typeof obj[i] === "object" && obj[i] !== null) {

        result[i] = deepCopy(obj[i]);

      } else {

        result[i] = obj[i];

      }

    }

  }

  return result;

}

// ES6最简方法

let result = [];

if (Array.isArray(arr)) {

  result = new Set(arr);

}

// 数组去重

function unique(arr) {

  if (!Array.isArray(arr)) {

    return;

  }

  let result = [];

  for (let i = 0; i < arr.length; i++) {

    if (result.indexOf(arr[i]) === -1) {

      result.push(arr[i]);

    }

  }

  return result;

}

// 数组对象排序，比较两个字符串

list.sort((a, b) => {

  return a.id.localeCompare(b.id);

});