#js 数组去重的最优方法 利用ES6的set
Set数据结构,它类似于数组,其成员的值都是唯一的。
利用Array.from将Set结构转换成数组
function dedupe(array){
return Array.from(new Set(array));
}
dedupe([1,1,2,3]) //[1,2,3]
拓展运算符(...)内部使用for...of循环
let arr = [1,2,3,3];
let resultarr = [...new Set(arr)];
console.log(resultarr); //[1,2,3]
#时间相关的一些方法
/**
- 计算时间差
- @param star 必须是时间戳
- @param diff 时间相差天数
- @returns {*} 日期字符串 */
// console.log(timeDifference(new Date(), -20))
function timeDifference(star, diff) {
//star必须是时间戳
//diff时间相差天数
var starTime = star;
if (star.length == 10) {
starTime = star * 1000;
}
var now = new Date(starTime); //当前日期
now.setDate(now.getDate() + diff);
return formatDate(now);
//格式化时间
function formatDate(date) {
var myyear = date.getFullYear();
var mymonth = date.getMonth() + 1;
var myweekday = date.getDate();
if (mymonth < 10) {
mymonth = "0" + mymonth;
}
if (myweekday < 10) {
myweekday = "0" + myweekday;
}
return (myyear + "-" + mymonth + "-" + myweekday);
}
}
/**
- 按照指定格式将日期转换成字符串
- @param format 日期格式
- @returns {*} 日期字符串 */
Date.prototype.format = function (format) {
var o = {
"M+": this.getMonth() + 1, //month
"d+": this.getDate(), //day
"h+": this.getHours(), //hour
"m+": this.getMinutes(), //minute
"s+": this.getSeconds(), //second
"q+": Math.floor((this.getMonth() + 3) / 3), //quarter
"S": this.getMilliseconds() //millisecond
}
if (/(y+)/.test(format)) format = format.replace(RegExp.$1,
(this.getFullYear() + "").substr(4 - RegExp.$1.length));
for (var k in o)if (new RegExp("(" + k + ")").test(format))
format = format.replace(RegExp.$1,
RegExp.$1.length == 1 ? o[k] :
("00" + o[k]).substr(("" + o[k]).length));
return format;
}
/**
- 获取一定时间周期的具体时间
- @param data 详情请看if判断
- @returns {*} 日期字符串 */
//console.log(getDataDay('yesterday'));
function getDataDay(data) {
/** * 时间日期类
*/
var now = new Date(); //当前日期
var nowDayOfWeek = now.getDay(); //今天本周的第几天
var nowDay = now.getDate(); //当前日
var nowMonth = now.getMonth(); //当前月
var nowYear = now.getYear(); //当前年
nowYear += (nowYear < 2000) ? 1900 : 0; //
if (data == 'today') {
var yesterday = new Date(nowYear, nowMonth, nowDay); //今天
return formatDate(yesterday);
} else if (data == 'yesterday') {
var yesterday = new Date(nowYear, nowMonth, nowDay - 1); //昨天
return formatDate(yesterday);
} else if (data == 'weekStart') {
//获取本周第一天日期
var weekStart = new Date(nowYear, nowMonth, nowDay + (1 - nowDayOfWeek));
return formatDate(weekStart);
} else if (data == 'weekEnd') {
//获取本周最后一天日期
var weekStart = new Date(nowYear, nowMonth, nowDay + (7 - nowDayOfWeek));
return formatDate(weekStart);
} else if (data == 'lastWeekStart') {
//获得上周第一天日期
var lastWeekStart = new Date(nowYear, nowMonth, nowDay + (-6 - nowDayOfWeek));
return formatDate(lastWeekStart);
} else if (data == 'lastWeekEnd') {
//获得上周最后一天日期
var lastWeekEnd = new Date(nowYear, nowMonth, nowDay - nowDayOfWeek);
return formatDate(lastWeekEnd);
} else if (data == 'monthStart') {
//本月第一天
var monthStartDate = new Date(nowYear, nowMonth, 1);
return formatDate(monthStartDate);
} else if (data == 'monthEnd') {
//本月最后一天
var monthStartDate = new Date(nowYear, nowMonth + 1, -1);
return formatDate(monthStartDate);
} else if (data == 'lastMonthStart') {
//上月第一天
var monthStartDate = new Date(nowYear, (nowMonth - 1), 1);
return formatDate(monthStartDate);
} else if (data == 'LastMonthEnd') {
//上月最后一天
var monthStartDate = new Date(nowYear, nowMonth, -1);
return formatDate(monthStartDate);
}
//格式化时间
function formatDate(date) {
var myyear = date.getFullYear();
var mymonth = date.getMonth() + 1;
var myweekday = date.getDate();
if (mymonth < 10) {
mymonth = "0" + mymonth;
}
if (myweekday < 10) {
myweekday = "0" + myweekday;
}
return (myyear + "/" + mymonth + "/" + myweekday);
}
}
#Cookie操作
function getCookie(c_name) {
if (document.cookie.length > 0) {
var c_start = document.cookie.indexOf(c_name + "=")
if (c_start != -1) {
c_start = c_start + c_name.length + 1;
var c_end = document.cookie.indexOf(";", c_start);
if (c_end == -1) c_end = document.cookie.length;
return unescape(document.cookie.substring(c_start, c_end));
}
}
return "";
}
function setCookie(c_name, value, expiredays) {
if (!expiredays) {
expiredays = 100;
}
var exdate = new Date();
exdate.setDate(exdate.getDate() + expiredays);
document.cookie = c_name + "=" + escape(value) + ((expiredays == null) ? "" : ";expires=" + exdate.toGMTString());
}
# 获取一个唯一ID JavaScript生成GUID的算法
全局唯一标识符(GUID,Globally Unique Identifier)也称作 UUID(Universally Unique IDentifier) 。
GUID是一种由算法生成的二进制长度为128位的数字标识符。GUID 的格式为“xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx”,其中的 x 是 0-9 或 a-f 范围内的一个32位十六进制数。在理想情况下,任何计算机和计算机集群都不会生成两个相同的GUID。
GUID 的总数达到了2^128(3.4×10^38)个,所以随机生成两个相同GUID的可能性非常小,但并不为0。GUID一词有时也专指微软对UUID标准的实现。
//算法1
function uuid() {
var s = [];
var hexDigits = "0123456789abcdef";
for (var i = 0; i < 36; i++) {
s[i] = hexDigits.substr(Math.floor(Math.random() * 0x10), 1);
}
s[14] = "4"; // bits 12-15 of the time_hi_and_version field to 0010
s[19] = hexDigits.substr((s[19] & 0x3) | 0x8, 1); // bits 6-7 of the clock_seq_hi_and_reserved to 01
s[8] = s[13] = s[18] = s[23] = "-";
var uuid = s.join("");
return uuid;
}
//算法2
function guid() {
return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
var r = Math.random()*16|0, v = c == 'x' ? r : (r&0x3|0x8);
return v.toString(16);
});
}
//算法3
function guid() {
return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
var r = Math.random()*16|0, v = c == 'x' ? r : (r&0x3|0x8);
return v.toString(16);
});
}
//算法3
function guid() {
function S4() {
return (((1+Math.random())*0x10000)|0).toString(16).substring(1);
}
return (S4()+S4()+"-"+S4()+"-"+S4()+"-"+S4()+"-"+S4()+S4()+S4());
}
//算法4
function uuid(len, radix) {
var chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'.split('');
var uuid = [], i;
radix = radix || chars.length;
if (len) {
// Compact form
for (i = 0; i < len; i++) uuid[i] = chars[0 | Math.random()*radix];
} else {
// rfc4122, version 4 form
var r;
// rfc4122 requires these characters
uuid[8] = uuid[13] = uuid[18] = uuid[23] = '-';
uuid[14] = '4';
// Fill in random data. At i==19 set the high bits of clock sequence as
// per rfc4122, sec. 4.1.5
for (i = 0; i < 36; i++) {
if (!uuid[i]) {
r = 0 | Math.random()*16;
uuid[i] = chars[(i == 19) ? (r & 0x3) | 0x8 : r];
}
}
}
return uuid.join('');
}
//这个可以指定长度和基数。比如:
// 8 character ID (base=2)
uuid(8, 2) // "01001010"
// 8 character ID (base=10)
uuid(8, 10) // "47473046"
// 8 character ID (base=16)
uuid(8, 16) // "098F4D35"