方法

遍历数组与对象的函数

function Foreach(obj,fn){
    var key;
    if(obj instanceof Array){
        obj.forEach((item,index)=>{
            fn(index,item);
        })
    }else{
        for(key in obj){
            fn(key,obj[key]);
        }
    }
}
// var obj = {x:100,y:900};
// Foreach(obj,(key,value)=>{console.log(key,value)});
var arr = [66,77,33]
Foreach(arr,(index,item)=>{console.log(index,item)});

获取2020-12-23格式的日期

方法1.	function getTime(ti){
            if(!ti){
                ti = new Date();
            }
            let year = ti.getFullYear();
            let month = ti.getMonth()+1;
            let date = ti.getDate();
            if(month < 10){
                month = '0' + month;
            }
            if(date < 10){
                date = '0' + date;
            }
            return year + '-' + month + '-' + date;
    	}
        let ti = new Date();
        let formatDate = getTime(ti) //"2020-12-23"
 
方法2. let time = new Date().toISOString().slice(0,10); 

查找url参数

const url = 'http://erp.yang800.cn/my-store/1609847898208?config_id=1604303484505114&page_title=%E6%88%91%E7%9A%84%E5%BA%97%E9%93%BA';

1.输入参数名获取值

function fn(url ,name){
      let search = url.slice(1);
      let param = search.split('&');
      for(let i = 0;i < param.length ;i++){
          var q = param[i].split('=');
          if(q[0] == name){
              return decodeURIComponent(q[1]);
          }
      }
}
console.log(fn(url , 'page_title'));

2.url解析为js对象 

function getUrlParams() {
  let search = window.location?.hash?.split('?')[1];
  let list = search?.split('&');
  let res = {};
  list?.forEach(val => {
    let q = val.split('=');
    res[q[0]] = decodeURIComponent(q[1]);
  })
  return res;
}

3.url解析为js对象

function getUrlParams() {
  const res = {};
  const list = new URLSearchParams(location.search);
  list.forEach((val, key) => {
    res[key] = decodeURIComponent(val);
  })
}

4.输入参数名获取值
function query(url, name){
    const param = new URLSearchParams(url);
    return param.get('name');
};
query(url, "name")



3.RegExp
const reg = new RegExp(`(^|&)${name}=(([^&]*)(&|$))`,'i');

防抖

用户输入暂停100ms才搜索 
用户搜索时快速输入 1、2 输入 1 时触发debounce函数的定时器时间没到还未执行
立即输入 2 了，就把 1 触发的setTimeout清除，执行2的定时器，也就达到了重新计时
function debounce(fn, delay) {
    let time = null;
    return function () {
        if (time) {
            clearTimeout(time);
        }
        time = setTimeout(() => {
            fn.apply(this, arguments)
            time = null
        },delay)
    }
}

节流

类似技能冷却，一直拖动方块获取坐标值也就会一直触发throttle函数，只需要在200ms执行一次
function throttle(fn, delay) {
    let time = null  
    return function () {
        if (time) {
            return ;
        }
    time = setTimeout(() => {
            fn.apply(this, arguments)
            time = null
        }, delay)
    }
}

向字符串中添加一个字符

 let str = text.split('')
 str.splice(4,0,'-')
 let date = str.join('');

递归

1.阶层
5 * 4 * 3 * 2 * 1
function jc(n){
   if(n == 1 || n == 0){
      return 1;
  }
  return n*jc(n - 1)
}
//用一个数组存储值
var fb = function () {
var memo = [0, 1];
var fib = function (n) {
  var result = memo[n];
  if (typeof result !== 'number') {
    result = fib(n - 1) + fib(n - 2);
    memo[n] = result;
  }
  return result;
}
return fib
}()
2.斐波拉契数列
1 1 2 3 5 8 13
function fb(n){
    if(n == 1 || n == 2){
        return 1;
    }
    return fb(n - 1) + fb(n - 2)
}

数组乱序排列

list.sort(function(){ return Math.random() -0.5 })

获取随机数，要求是长度一致的字符串格式

let num = Math.random() * 1000;
num += '';
let newNum = num.slice(0,6);

数组拍平

flat(Infinty)

set 无序，不能重复

function unique(arr){ const set = new set(arr); return [...set] }; unique(11,22,33,44,11);

数据打乱重拍

let nums = [1,2,3,4,5,6];

function mySort(_nums){
    let nums = [..._nums]
    let arr = []
    while(arr.length < nums.length){
        let index  = parseInt(Math.random() * nums.length);
        if(nums[index]){
            arr.push(nums[index]);
            nums[index] = null;
        }
    }
    console.log(arr);
}

function mySort2(_nums){
    let nums = [..._nums]
    let arr = []
    while(nums.length > 0){
        let index  = parseInt(Math.random() * nums.length);
        arr.push(nums[index]);
        nums.splice(index,1)
    }
    console.log(arr);
}

nums.sort(() => Math.random() - Math.random())

获取当前时间

getTime() {
    let weeks = ['天', '一', '二', '三', '四', '五', '六'];
    let myTime = new Date();
    let year = myTime.getFullYear();
    let month = myTime.getMonth() + 1;
    let day = myTime.getDate();
    let week = myTime.getDay();
    let hours = myTime.getHours();
    let minutes = myTime.getMinutes();
    let seconds = myTime.getSeconds();
    let timeStr = '今天是：' + year + '年' + month + '月' + day + '日 星期' + weeks[week] + hours + '时' + minutes + '分' + seconds + '秒';
}

获取当前实时时间

<div id="currentTime"></div>

data() {
    return {
         timer: null
    }
}

created() {
    let timer = setInterval(() => {
        this.fnDate();
    }, 1000);
    // 离开当前页面时销毁定时器
    this.$once('hook:beforeDestroy', () => {
        clearInterval(timer);
        this.timer = null;
    })
},
//js 获取当前时间
fnDate() {
    let oDiv = document.getElementById("currentTime");
    let date = new Date();
    let year = date.getFullYear();
    let month = date.getMonth();
    let data = date.getDate();
    let hours = date.getHours();
    let minute = date.getMinutes();
    let second = date.getSeconds();
    let time = year + "-" + this.fnW((month + 1)) + "-" + this.fnW(data) + " " + this.fnW(hours) + ":" + this.fnW(minute) + ":" + this.fnW(second);
    let a = new Array("日", "一", "二", "三", "四", "五", "六");
    let week = new Date().getDay();
    let str = "星期" + a[week];
    oDiv.innerHTML = time + "　" + str;
},
//补位 当某个字段不是两位数时补0
fnW(str) {
    return str > 9 ? str : "0" + str;
},