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为什么null>=0是true

1

1

数据类型

class="cursor-pointer"> 详细描述

class="cursor-pointer"> 截图

class="cursor-pointer"> 代码

null>=0;
true

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洗牌算法和Math.random随机数有什么区别吗？

0

1

函数操作DOM 表达式和运算符

class="cursor-pointer"> 详细描述

class="cursor-pointer"> 截图

class="cursor-pointer"> 代码

function suiji(){
	for (var i=qq.length-1; i>=0; i--) {
		var aaa = Math.floor(Math.random()*(i+1));//产生随机数
		var bbb = qq[aaa];
		qq[aaa] = qq[i];
		qq[i] = bbb;	
	}
	return qq;

function ncolor(){
	var r = Math.floor(Math.random()*256);
	var g = Math.floor(Math.random()*256);
	var b = Math.floor(Math.random()*256);
	return "rgb("+r+","+g+","+b+")";
}//随机颜色

该问题已被官方收录

数组随机打印出来,控制台报错

1

1

控制流程语句数据类型

class="cursor-pointer"> 详细描述

class="cursor-pointer"> 截图

class="cursor-pointer"> 代码

. var arr=new Array(3);
    var arr1=new Array(3);
    for(var i=0;i<arr.length;i++) {
        var a= parseInt(Math.random()*9);
        console.log(a);
        if (i==0) {
            arr[i] = a;
        } else {
            for (var j = 0; j < i; j++) {
                if (a == arr[j]) {
                    i--
                }
                else {
                    arr[i] = a;
                }
            }
        }
    }
for (var i=0;i<arr1.length;i++){
        var a=parseInt(Nath.random()*9);
        if(i=0){
            arr1[i]=a;
        }
        else {
            for(var j=0;j<i;j++){
                if (a==arr1[j]){
                    i--
                }
                else {
                    arr1[i]=a;
                }
            }
        }
}

该问题已被官方收录

js开启严格模式下疯狂报错

1

1

js基础

class="cursor-pointer"> 详细描述

class="cursor-pointer"> 截图

class="cursor-pointer"> 代码

app.controller('BackCtrl', function ($scope, $location, $http, $state) {
    "use strict"

    //后台页面控制器

    //菜单
    $scope.menus = [{
            title: '信息管理',
            lists: [{
                    content: '公司列表',
                    url: 'backstage.company'
                },
                {
                    content: '职位列表',
                    url: 'backstage.post'
                },
            ],
            open: false,
            sref: ''
        },
        {
            title: '内容管理',
            lists: [{
                content: 'Article管理',
                url: 'backstage.list'
            }, ],
            open: false,
            sref: ''
        },
        {
            title: '后台管理',
            lists: [{
                    content: '账号管理',
                    url: 'backstage.account'
                },
                {
                    content: '角色管理',
                    url: 'backstage.role'
                },
                {
                    content: '修改管理',
                    url: 'backstage.revision'
                },
                {
                    content: '模块管理',
                    url: 'backstage.module'
                },
            ],
            open: false,
            sref: ''
        },
    ]
    //验证是否登录，未登录禁止访问
    let logined = JSON.parse(sessionStorage.getItem('logined'));
    if (logined !== 0) {
        alert('账号未登录');
        $state.go('login');
    }
    //注销登录
    $scope.logout = function () {
        $http({
            method: 'post',
            url: '/carrots-admin-ajax/a/logout',
            header: {
                'Content-Type': 'application/x-www-form-urlencoded'
            }
        }).then(function (res) {
            console.log(res)
            if (res.data.code === 0) {
                $state.go('login');
                sessionStorage.clear();
            }
        })
    }

    // 子菜单状态保存
    // let currentUrl = $location.path(); //获取当前路由
    // currentUrl = currentUrl.replace(/\//g, '.'); //正则替换掉斜杠
    // currentUrl = currentUrl.slice(1) //删除最前面的斜杠
    // $scope.currentUrl = currentUrl;
    //风琴菜单状态保存
    
    $scope.navtitle = function (index) {
        console.log(index);
        console.log(!$scope.menus[index].open);
        sessionStorage.setItem("session", index)
        sessionStorage.setItem("index0",  !$scope.menus[index].open)
    }
    if (window.sessionStorage.getItem("session") !== null) {
        session = parseInt(window.sessionStorage.getItem("session"))
        index0 = window.sessionStorage.getItem("index0")
        console.log(index0);
        console.log(session);
        $scope.menus[session].open = index0
    }
    //侧边栏高亮
    $scope.aaa = function (x, y) {
        console.log(x, y)
        for (let r = 0; r < $scope.menus.length; r++) {
            for (let i = 0; i < $scope.menus[r].lists.length; i++) {
                $scope.menus[r].lists[i].isOrgancheck = false;
            }
        }
        $scope.menus[x].lists[y].isOrgancheck = true;
        sessionStorage.setItem("sessionx", x)
        sessionStorage.setItem("sessiony", y)
    }
    sessionx = window.sessionStorage.getItem("sessionx")
    sessiony = window.sessionStorage.getItem("sessiony")
    if (sessionx !== null && sessiony !== null) {
        $scope.menus[sessionx].lists[sessiony].isOrgancheck = true;
    }
}

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随机数去重复的问题？

1

1

函数操作DOM 数据类型

class="cursor-pointer"> 详细描述

class="cursor-pointer"> 截图

class="cursor-pointer"> 代码

var box = $(".box");
var time;


function suiji() {
    var r = Math.floor(Math.random() * 256);
    var g = Math.floor(Math.random() * 256);
    var b = Math.floor(Math.random() * 256);
    return "rgb(" + r + "," + g + "," + b + ")";
}


function org() {
    box[0].style.backgroundColor = "orange";
    box[1].style.backgroundColor = "orange";
    box[2].style.backgroundColor = "orange";
    box[3].style.backgroundColor = "orange";
    box[4].style.backgroundColor = "orange";
    box[5].style.backgroundColor = "orange";
    box[6].style.backgroundColor = "orange";
    box[7].style.backgroundColor = "orange";
    box[8].style.backgroundColor = "orange";
}
// (box1!=box2&&box1!=box3&&box2!=box3)
// (box1!=box2 || box1,box2!=box3 || box2,box1!=box3 || box3)
function df() {
    org();
    var box1 = Math.floor(Math.random() * box.length);
    var box2 = Math.floor(Math.random() * box.length);
    var box3 = Math.floor(Math.random() * box.length);
    if {

        box[box1].style.backgroundColor = suiji();
        box[box2].style.backgroundColor = suiji();
        box[box3].style.backgroundColor = suiji();
    }
    else {
        df()
    }
}

$("#btn1").click(function dfd() {
    clearInterval(time);
    time = setInterval(df, 1000);
});
$("#btn2").click(function () {
    org();
    clearInterval(time);
});

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对一个数组进行随机排序有哪些写法？

1

1

变量表达式和运算符函数

class="cursor-pointer"> 详细描述

class="cursor-pointer"> 截图

class="cursor-pointer"> 代码

 function _3number() {
            var arr = []
            for (i = 0; i < 9; i++) {
                arr.push(bg());
            }

            arr.sort(function () {
                return Math.random() - 0.5
            })
            var a = arr[0];
            var b = arr[1];
            var c = arr[2];
            return(a+b+c);
        }

function number() { // 随机0-9数字函数
            return Math.floor(Math.random() * 9);
        }

该问题已被官方收录

如何随机取得小格子中的3个格子

1

1

js基础

class="cursor-pointer"> 详细描述

class="cursor-pointer"> 截图

class="cursor-pointer"> 代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8" name ="viewport" content ="width=device-width,initial-scale=1.0">
    <title>九宫格</title>
    <link href="task1.css" rel="stylesheet" type="text/css"/>
</head>
<body>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
    <button id="start" onclick="start()">开始闪</button>
    <button id="end" onclick="end()">结束闪</button>
    <script src="task1.js"></script>
</body>
</html>

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获取三个不会重复的背景颜色

1

1

控制流程语句 js基础

class="cursor-pointer"> 详细描述

class="cursor-pointer"> 截图

class="cursor-pointer"> 代码

 //获取rgb的随机颜色
        function color(){
            var rgb;
             r = Math.floor(Math.random()*256);
             g = Math.floor(Math.random()*256);
             b = Math.floor(Math.random()*256);
            rgb ="rgb("+r+","+g+","+b+")"
            console.log(rgb);
            return rgb;
        }
        //获取三个随机盒子
        function box(){
             //当第一个盒子和第二个盒子相同的时候，或者第……，会重新获取三个盒子
             while(first == second || second == third || first==third){
                var first = Math.floor(Math.random()*9);
                var second =  Math.floor(Math.random()*9);
                var third =  Math.floor(Math.random()*9);
                console.log(first,second,third);
            }
            //给随机的三个盒子赋值上随机背景颜色rgb
            itme[first].style.backgroundColor = color()
            itme[second].style.backgroundColor = color()
            itme[third].style.backgroundColor = color()
        }

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九宫格随机

0

1

事件

class="cursor-pointer"> 详细描述

class="cursor-pointer"> 截图

class="cursor-pointer"> 代码

var list=document.getElementsByClassName("let_style");//获取节点
var run=document.getElementById("run");
var stop=document.getElementById("stop");
var time;//???

function begin(){
    var one=Math.floor(Math.random()*list.length);
    var two=Math.floor(Math.random()*list.length);
    var three=Math.floor(Math.random()*list.length);
if(one==two || two==three || three==one) {
    one=Math.floor(Math.random()*list.length);
    two=Math.floor(Math.random()*list.length);
    three=Math.floor(Math.random()*list.length);

}
console.log(one,two,three)
list[one].style.background='rgb'+colors();
list[two].style.background='rgb'+colors();
list[three].style.background='rgb'+colors();

// console.log(one)
//     console.log(two)
//     console.log(three)
}
  

function colors(){
    var rgb;
    var r=Math.floor(Math.random()*265);
    var g=Math.floor(Math.random()*265);
    var b=Math.floor(Math.random()*265);
 
    rgb='('+r+','+g+','+b+')';
    return rgb;
}

run.onclick=function(){
    clearInterval(time);
    time=setInterval(function(){
        for(var i=0;i<list.length;i++){
            list[i].style.backgroundColor='';
        }
        begin();
    },1000);
}
stop.onclick=function(){
    clearInterval(time);
    for(var i=0;i<list.length;i++){
        list[i].style.backgroundColor='';
    }
}

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true和false怎么不一样啊？

0

1

数据类型函数

class="cursor-pointer"> 详细描述

class="cursor-pointer"> 截图

class="cursor-pointer"> 代码

var a=1;
undefined
true&&(a=2);
2
true||(a=3);
true
var b=5;
undefined
false&&(b=6);
false
false||(b=7);
7

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