[英]How to handle an async function that depends on multiple other async functions
I have an asynchronous function that works with the result of two other async functions. 我有一个异步函数,可以处理另外两个异步函数的结果。
Till now what I was doing is that I write function2 in the callback function1 and function2 in the callback of function2 直到现在我正在做的是我在回调函数1中编写function2,在function2的回调中编写函数2
function1(callbackFunction() {
function2(callbackFunction() {
function3()
})
})
Is there any other way to handle this. 有没有其他办法来处理这个问题。 I work usually with JavaScript code in client side and in nodeJs. 我通常使用客户端和nodeJs中的JavaScript代码。
My scenario is that for function2 I don't need output from function1. 我的情况是,对于function2,我不需要function1的输出。 In another words function1 and function2 are independent; 换句话说,function1和function2是独立的; but function3 is dependent on function1 and function2. 但是function3依赖于function1和function2。
I want my function2 to run independent on function1 but function3 to run dependent on both functio1 and function2. 我希望我的function2在function1上独立运行,但是function3依赖于functio1和function2来运行。
Is there anything like 有没有像
function1();
function2();
when(funtion1.complete && funtion2.complete) {
function3();
}
There are some good libraries to deal with orchestrating asynchronous functions. 有一些很好的库来处理编排异步函数。 async
and q
(or other Promises/A libraries) help. async
和q
(或其他Promises / A库)有帮助。
If function2
does not depend on the result of function1
, you can execute them in parallel. 如果function2
不依赖于function1
的结果,则可以并行执行它们。 Here's how it looks using async
(these examples assume that your callback has a function(err, result)
signature, which is the defacto pattern for Node: 以下是使用async
外观(这些示例假设您的回调具有function(err, result)
签名,这是Node的实际模式:
async.parallel([
function(callback) { function1(callback); },
function(callback) { function2(callback); }
], function(err, values) {
function3(values[0], values[1]);
});
If function2
depends on the result from function1
, waterfall
may be a better pattern: 如果function2
取决于从结果function1
, waterfall
可能是一个更好的模式:
async.waterfall([
function(callback) { function1(callback); },
function(result, callback) { function2(result, callback); },
function(result, callback) { function3(result, callback); },
]);
Personally, I like q
, because you can pass promises around and do all kinds of nifty stuff. 就个人而言,我喜欢q
,因为你可以通过承诺并做各种漂亮的东西。 Here's how this would look using that: 以下是使用它的方式:
q.nfcall(function1)
.then(function(result) { return q.nfcall(function2); })
.then(function(result) { return q.nfcall(function3); })
.fail(function(err) {
// If any of them fail, this is called.
});
Or if function1
and function2
can be done in arbitrary order: 或者,如果function1
和function2
可以按任意顺序完成:
q.all([q.nfcall(function1), q.nfcall(function2)])
.then(function(values) { function3(values[0], values[1]); })
.fail(function(err) {
});
Here is a solution that I baked. 这是我烘焙的解决方案。 You can try a call manager to call the dependant functions 您可以尝试使用呼叫管理器来调用相关功能
var func1 = function() {
console.log("Dependant call ... " + 1);
};
var func2 = function() {
console.log("Dependant call ... " + 2);
};
var func3 = function() {
console.log("Dependant call ... " + 3);
};
var func4 = function() {
console.log("Dependant call ... " + 4);
};
var CallManager = function(funcs_config) {
var _this = this;
_this.functions = funcs_config;
_this.callAsynchronous = function(f) {
if (f != undefined) {
for (var i = 0; i < f.length; i++) {
f[i].call(function() {
this.callAsynchronous(f.splice(0,1));
});
}
return;
}
for (var func in _this.functions) {
if (_this.functions[func].length == 0) {
//not dependent to any function
} else {
console.log('Calling....' + func);
_this.callAsynchronous(_this.functions[func]);
eval(func +'();');
}
}
};
return _this;
};
var callManager = new CallManager({
//dependency configuration
func2: [func1], //func2 depends on func1
func3: [func2],
func4: [func1, func3] //func4 depends on both func1 and func3
});
callManager.callAsynchronous();
With the current config provided above, when it is run the output is given as - 使用上面提供的当前配置,当它运行时,输出为 -
Calling....func2
Dependant call ... 1
Dependant call ... 2
Calling....func3
Dependant call ... 2
Dependant call ... 3
Calling....func4
Dependant call ... 1
Dependant call ... 3
Dependant call ... 4
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