function sum(x,y,z){
        let total = 0;
        if(x)total+=x;
        if(y)total+=y;
        if(z)total+=z;
    }
    sum(5,"",9);
    function sum2(...m){
        let total = 0;
        for(var i of m){
            total += i;
        }
        console.log(`total${total}`)
    }
    sum2(4,8,9,10,5);
    let sum3 = (...m)=>{
      let total = 0;
      for(var i of m){
        total += i;
      }
      console.log(`total${total}`)
    }
    sum3(4,8,9,10,5);
    var [x,y] = [4,8];
    console.log(...[4,8])
    let arr1 = [1,3];
    let arr2 = [4,8];
    console.log("concat:"+arr1.concat(arr2));
    //[...arr1,...arr2];
    let [a,b,c]="ES6";
    console.log(a);//输出E

let checkLogin = function(){
        return new Promise(function(resolve,reject){
            let flag = document.cookie.indexOf("userId")>-1?true:false;
            if(flag=true){
                resolve({
                    status :0,
                    result:true
                })
            }else{
                reject("error")
          }
        })
    };
    let getUserInfo = ()=>{
        return new Promise((resolve,reject)=>{
            let userInfo={
                userId:"101 "
            }
            resolve(userInfo);
      })
    };
    checkLogin().then((res)=>{
        if(res.status == 0){
            console.log("login success")
          return getUserInfo();
        }
    }).catch((error)=>{
        console. log(`error:${error}`);
    }).then((res2)=>{
        console.log(`userId${res2.userId}`)
    })
    Promeise.all([checkLogin(),getUserInfo( )]).then(([res1,res2])=>{
        console.log(`result:${res1.result},result:${res2.result}`)
    })

 //promise
    let checkLogin = function(){
        return new Promise(function(resolve,reject){
            let flag = document.cookie.indexOf("userId")>-1?true:false;
            if(flag=true){
                resolve({
                    status:0,
                    result:true
                })
            }else{
                reject("error")
          }
        })
    };
    let getUserInfo = ()=>{
        return new Promise((resolve,reject)=>{
            let userInfo={
                userId:"101"
            }
            resolve(userInfo);
      })
    };
    checkLogin().then((res)=>{
        if(res.status == 0){
            console.log("login success")
          return getUserInfo();
        }
    }).catch((error)=>{
        console.log(`error:${error}`);
    }).then((res2)=>{
        console.log(`userId${res2.userId}`)
    });
    Promeise.all([checkLogin(),getUserInfo()]).then(([res1,res2])=>{
        console.log(`result:${res1.result},result:${res2.result}`)
    })