new Promise(function(resolve,reject){
let i = 3;
setTimeout(function(){
if(i>5){
resolve(i);
}else{
reject(i);
}
},2000);
}).then(function(index){
console.log(index);
},function(index){
console.log(index);
});
function demo(callback,callback2){
let i = 3;
setTimeout(function(){
if(i>5){
callback(i);
}else{
callback2(i);
}
},1000);
}
demo(function(index){
console.log(index);
},function(index){
console.log(index);
});