LCache缓存类

class LCache{
    constructor(load,exec){
        this.load=load;//加载函数
        this.exec=exec;//执行函数
        this.maxLen=100;//最大缓存数

        this.nearTimeMap={};//最近访问时间
        this.resMap={};//缓存

        this.paramsMap={};//当前参数
        this.callbackMap={};//当前回调

        this.loadedI=-1;//记录url 加载完成位置

        this.curIMap={};//访问的位置
        this.isloadMap={};//是否正在加载

        this.loadbackMap={};//接口加载完成回调
        this.numMap={};//被访问几次
        this.lnumMap={};//被加载几次
        this.allUrlArr=[];
        this.itemArr={};
    }
    loadAll(arr,callback){
        const startI=this.allUrlArr.length;
        const urlArr=[];
        if(arr&&arr.length>0){
            for(let i=0;i<arr.length;i++){
                if(arr[i]){
                    urlArr.push(arr[i])
                    this.allUrlArr.push(arr[i])
                }
            }
        }
        if(urlArr.length===0){
            urlArr.push('');
            this.allUrlArr.push('');
        }
        const endI=this.allUrlArr.length;
        //缓存回调
        this.paramsMap[endI]=urlArr;
        this.callbackMap[endI]= (k)=> {
            const urlArr=this.paramsMap[k];
            callback(urlArr.map( (url)=> {
                return this.resMap[url]
            }));
            delete this.paramsMap[k];
            if(k-1===this.loadedI){
                //清理缓存
                this.clearCache();
            }
        };
        console.log('加载资源',urlArr)

        for(let i=startI;i<endI;i++){
            this.loadItem(this.allUrlArr[i],i, (item)=> {
                this.itemArr[item.curI]=item;
                if(item.curI-this.loadedI===1){
                    let k=item.curI;
                    while (k<this.allUrlArr.length&&this.itemArr[k]){
                        this.loadedI=k;
                        this.exec(this.itemArr[k]);
                        delete this.itemArr[k];
                        if(this.callbackMap[k+1]){
                            this.callbackMap[k+1](k+1);
                            delete this.callbackMap[k+1];
                        }
                        k=k+1;
                    }
                }
            })
        }
    }
    loadItem(url,curI,callback){
        this.numMap[url]=this.numMap[url]||0;
        this.lnumMap[url]=this.lnumMap[url]||0;
        this.nearTimeMap[url]=new Date().getTime();
        this.numMap[url]++;
        if(url&&!this.resMap[url]){
            this.loadbackMap[this.numMap[url]+'-'+url]=callback;
            this.curIMap[this.numMap[url]+'-'+url]=curI;

            if(!this.isloadMap[url]){
                this.isloadMap[url]=true;
                this.load(url, (text)=> {
                    delete this.isloadMap[url];
                    this.lnumMap[url]++;
                    this.resMap[url]=text;
                    for(let i=1;i<this.numMap[url]+1;i++){
                        if(this.loadbackMap[i+'-'+url]){
                            this.loadbackMap[i+'-'+url]({
                                url:url,
                                text:text,
                                curI:this.curIMap[i+'-'+url],
                                num:i,
                                lnum:this.lnumMap[url],
                            });
                            delete this.loadbackMap[i+'-'+url];
                        }
                    }

                })
            }
        }else{
            setTimeout( () =>{
                callback({
                    url:url,
                    curI:curI,
                    text:this.resMap[url],
                    num:this.numMap[url],
                    lnum:this.lnumMap[url]
                });
            },0)
        }
    }
    //清理缓存,按照访问时间排序
    clearCache(){
        console.log('clearCache')
        const urls=Object.keys(this.resMap)
        if(urls.length>this.maxLen){
            urls.sort( (url1,url2)=> {
                if(this.nearTimeMap[url1]-this.nearTimeMap[url2]>0){
                    return 1;
                }else{
                    return -1
                }
            })
            const delArr=urls.slice(0,urls.length-this.maxLen);
            for(let i=0;i<delArr.length;i++){
                const url=delArr[i];
                delete this.resMap[url];
                delete this.nearTimeMap[url];
            }
        }
    }

}

function load(time,callback) {
    setTimeout(function () {
        callback('res'+time)
    },time)
}
function exec(item) {
    console.log(item)
    if(item.num===1){

    }

}
const aLCache=new LCache(load,exec)

aLCache.loadAll([200,100],function (resMap) {
    console.log('callback 1',resMap)
    aLCache.loadAll([],function (resMap) {
        console.log('callback 5')
    })
})

aLCache.loadAll([20,10],function (resMap) {
    console.log('callback 2')
    aLCache.loadAll([],function (resMap) {
        console.log('callback 6')
    })

})
aLCache.loadAll([200,100],function (resMap) {
    console.log('callback 3')
})
aLCache.loadAll([20,10],function (resMap) {
    console.log('callback 4')
    console.log(resMap)
})