如何将回调函数作为参数传递给另一个函数

我是 Ajax 和回调函数的新手，如果我把概念弄错了，请原谅我。

问题: 是否可以将 回调函数作为参数发送给将执行回调的另一个函数？

function firstFunction(){
//some code


//a callback function is written for $.post() to execute
secondFunction("var1","var2",callbackfunction);
}


function secondFunction(var1, var2, callbackfunction) {
params={}
if (event != null) params = event + '&' + $(form).serialize();


// $.post() will execute the callback function
$.post(form.action,params, callbackfunction);
}
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最佳答案

Yup. Function references are just like any other object reference, you can pass them around to your heart's content.

Here's a more concrete example:

function foo() {
console.log("Hello from foo!");
}


function caller(f) {
// Call the given function
f();
}


function indirectCaller(f) {
// Call `caller`, who will in turn call `f`
caller(f);
}


// Do it
indirectCaller(foo); // logs "Hello from foo!"

You can also pass in arguments for foo:

function foo(a, b) {
console.log(a + " + " + b + " = " + (a + b));
}


function caller(f, v1, v2) {
// Call the given function
f(v1, v2);
}


function indirectCaller(f, v1, v2) {
// Call `caller`, who will in turn call `f`
caller(f, v1, v2);
}


// Do it
indirectCaller(foo, 1, 2); // logs "1 + 2 = 3"

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Yes of course, function are objects and can be passed, but of course you must declare it:

function firstFunction(){
//some code
var callbackfunction = function(data){
//do something with the data returned from the ajax request
}
//a callback function is written for $.post() to execute
secondFunction("var1","var2",callbackfunction);
}

an interesting thing is that your callback function has also access to every variable you might have declared inside firstFunction() (variables in javascript have local scope).

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If you google for javascript callback function example you will get Getting a better understanding of callback functions in JavaScript

This is how to do a callback function:

function f() {
alert('f was called!');
}


function callFunction(func) {
func();
}


callFunction(f);
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Also, could be simple as:

if( typeof foo == "function" )
foo();
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Example for CoffeeScript:

test = (str, callback) ->
data = "Input values"
$.ajax
type: "post"
url: "http://www.mydomain.com/ajaxscript"
data: data
success: callback


test (data, textStatus, xhr) ->
alert data + "\t" + textStatus
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You can use JavaScript CallBak like this: 

var a;


function function1(callback) {
console.log("First comeplete");
a = "Some value";
callback();
}
function function2(){
console.log("Second comeplete:", a);
}




function1(function2);

Or Java Script Promise:

let promise = new Promise(function(resolve, reject) {
// do function1 job
let a = "Your assign value"
resolve(a);
});


promise.then(


function(a) {
// do function2 job with function1 return value;
console.log("Second comeplete:", a);
},
function(error) {
console.log("Error found");
});

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