• 輸出為10

var fnArr = [];
for (var i = 0; i < 10; i ++) {
    !function (j) {
        fnArr[j] =  function(){
            return j;
    }
    }(i)
}
console.log( fnArr[3]() );

或者

var fnArr = [];
for (var i = 0; i < 10; i ++) {
    fnArr[i]=function (i) {
        return function () {
            console.log(i)
        }
    }(i)
}
console.log( fnArr[3]() );

  var Car = (function () {
        var speed = 0;

        function setSpeed(s) {
             return speed = s
        }
        function getSpeed(){
            console.log(speed)
        }
        function accelerate(){
            return speed += 10
        }
        function decelerate() {
            return speed -= 10
        }
        function getStatus() {
            if (speed>0){
                return 'running'
            }else{
                return 'stop'
            }
        }
        return{
            setSpeed: setSpeed,
            getSpeed: getSpeed,
            accelerate: accelerate,
            decelerate: decelerate,
            getStatus: getStatus,
        }
    })()
    Car.setSpeed(30);
    Car.getSpeed(); //30
    Car.accelerate();
    Car.getSpeed(); //40;
    Car.decelerate();
    Car.decelerate();
    Car.getSpeed(); //20
    Car.getStatus(); // 'running';
    Car.decelerate();
    Car.decelerate();
    Car.getStatus();  //'stop';

var a = 1;
setTimeout(function(){
    a = 2;
    console.log(a);
}, 0);
var a ;
console.log(a);
a = 3;
console.log(a);
//輸出為1   3    2
setTimeout在當(dāng)前代碼隊(duì)列執(zhí)行結(jié)束后再執(zhí)行，異步執(zhí)行。

var flag = true;
setTimeout(function(){
    flag = false;
},0)
while(flag){}
console.log(flag);
//不輸出，因?yàn)閣hile(flag)一直為true，所以一直循環(huán)，setTimeout無(wú)法被執(zhí)行。

for(var i=0;i<5;i++){
    setTimeout(function(){
         console.log('delayer:' + i );
    }, 0);
    console.log(i);
}
//輸出0 1 2 3 4 delayer:5 delayer:5 delayer:5 delayer:5 delayer:5

for(var i=0;i<5;i++){
        !function (i) {
            return setTimeout(function(){
                console.log('delayer:' +i );
            }, 0)
        }(i)
        console.log(i);
    }

6.如何獲取元素的真實(shí)寬高

let style= window.getComputedStyle(element);
console.log(style.height, style.width);

7.URL 如何編碼解碼？為什么要編碼？

編碼的方式有兩種，第一種是使用encodeURI();參數(shù)為一個(gè)url字符串或字符串對(duì)象，通過(guò)這種方式編碼的url相比encodeURIComponent()編碼的將會(huì)把元字符和語(yǔ)義字符之外的字符，都進(jìn)行轉(zhuǎn)義,而后者除了語(yǔ)義字符之外的字符，元字符也會(huì)被轉(zhuǎn)義。因此，它的參數(shù)通常是URL的路徑或參數(shù)值，而不是整個(gè)URL。答:編碼的作用無(wú)非就是為了使用起來(lái)更加方便輕巧且易于區(qū)分，避免造成誤會(huì)比如當(dāng)我門要返回一個(gè)網(wǎng)址的時(shí)候，?back=xxx&value = return.這樣便不會(huì)把后面的value也當(dāng)成了前一個(gè)網(wǎng)頁(yè)的參數(shù)值.

function isAndroid(){
    return /Android/.test(navigator.userAgent);
}
funcnction isIphone(){
    return /iPhone/.test(navigator.userAgent);
}
function isIpad(){
    return /iPad/.test(navigator.userAgent);
}
function isIOS(){
    return /(iPad)|(iPhone)/i.test(navigator.userAgent);
}