寫了個例子，可以在chrome的控制臺里直接執行
(()=>{
Promise.allInOrder = (promises, thenForEach)=>{
let callBackQueue = new Array(promises.length);
let thenCallbackQueue = new Array(promises.length);
let queueExecutor = ()=>{
for(let i=0,l=callBackQueue.length;i<l;i++){
if(callBackQueue[i] == void(0)){
// undefined means this task is not done yet
return;
}else{
// execute callback
callBackQueue[i]();
// set this callback to null since it has been executed
callBackQueue[i] = ()=>{};
}
}
// when reach here, it means all callbacks been executed
Promise.all(thenCallbackQueue).then(ds=>{
allPromiseResolver(ds);
});
};
let allPromiseResolver = null,
allPromiseRejector = null;
for(let i=0,l=promises.length;i<l;i++){
promises[i].then(d=>{
callBackQueue[i] = function(){
thenCallbackQueue[i] = new Promise((resolve, reject)=>{
let result = thenForEach(d);
resolve(result);
});
};
queueExecutor();
});
}
return {
all: callback=>{
return new Promise((resolve, reject)=>{
allPromiseResolver = resolve;
allPromiseRejector = reject;
}).then(ds=>{
callback(ds);
});
}
}
};
})();
// test
(()=>{
let timeConsumingFunc = param=>new Promise(
(resolve)=>{
let timeout = Math.random() * 5000;
console.log(`task ${param} will be resolved in ${timeout}ms`);
setTimeout(()=>{
console.log(`${param} resolved`);
resolve(param+10);
}, timeout);
}
);
Promise
.allInOrder(
[timeConsumingFunc(1), timeConsumingFunc(2), timeConsumingFunc(3)],
d=>{
console.log(d);
return d+20;
}
)
.all((ds)=>{console.log(`all method called`);console.log(ds);})
})();
