javascript模擬原生Promise語法

研究Promise時，想過本身模擬下這個異步機制，今天封裝了一套簡易代碼：

let Pms=null;
(function () {
    function execFn(pms,type,data) {
        let {[type+'Arr']:arr,status}=pms;
        if (status != "pending" ) return;
        arr.forEach((fn,index)=>{
            fn.call(pms, data);
        });
        pms.status= type == "suc"? "fulfilled":"rejected";
        pms.args=data;
    }
    Pms=class{
       constructor(callBack){
           this.status="pending";
           this.sucArr=[];
           this.errorArr=[];
           this.args="";
           callBack.apply(null, [execFn.bind(null, this,'suc'),execFn.bind(null, this,'error')]);
       }
        then(sucFn,errorFn){
            this.sucArr.push(sucFn);
            if (this.status == "fulfilled"){
                sucFn.call(this, this.args);
            }
            if (typeof errorFn != "undefined"){
                this.catch(errorFn);
            }
        }
        catch(errorFn){
            this.errorArr.push(errorFn);
            if (this.status == "rejected"){
                errorFn.call(this, this.args);
            }
        }
    }
})();

線上代碼測試地址爲：
線上測試地址