class _Promise{
    constructor(callBack){
        if(typeof callBack !== 'function'){
            return false
        }
        this.state = 'p'
        this.value = ''
        this.reason = ''
        this.success_fn = []
        this.err.fn = []
        const resolve = value => {
            this.state = 'f'
            this.value = value
        }
        const reject = value => {
            this.state = 'r'
             this.reason = value
        }
        callBack(resolve,reject)
    }
    // then函数
    then(onFulfilled,onRejected){
        if(typeof onFulfilled !== 'function'){
            onFulfilled = value => value
        }
         if(typeof onRejected !== 'function'){
            onRejected = value => value
        }
        setTimeout(()=>{
            if(this.state === 'f'){
                onFulfilled(this.value)
            }
             if(this.state === 'r'){
                onRejected(this.reason)
            }
        })
    }
}
_Promise.prototype.all = function(promises) {
  let results = [];
  let promiseCount = 0;
  let promisesLength = promises.length;
  return new _Promise(function(resolve, reject) {
    for (let val of promises) {
      _Promise.resolve(val).then(function(res) {
        promiseCount++;
        // results.push(res);
        results[i] = res;
        // 当所有函数都正确执行了，resolve输出所有返回结果。
        if (promiseCount === promisesLength) {
          return resolve(results);
        }
      }, function(err) {
        return reject(err);
      });
    }
  });
};
console.log(1)
new _Promise((resolve,reject)=>{
    console.log(2)
    resolve(3)
}).then(res=>{
    console.log(res)
})
let p1 = new _Promise((resolve, reject) => {
  resolve('成功了')
})

let p2 = new _Promise((resolve, reject) => {
  resolve('success')
})
_Promise.all([p1,p2]).then(res=>{
    console.log(res)
})
console.log(4)