如果我有一个函数定义的前面，做我需要包括指定它应该用于一个成功的回调时，括号？

会有什么区别，如果我这样做？

在

 函数fish_food（）{//做一些事情}

$阿贾克斯（{
    网址：'/'，
    成功：fish_food
}）;
 

或

  $。阿贾克斯（{
    网址：'/'，
    成功：fish_food（）
}）;
 

解决方案

fish_food 自己（不含括号）作为一个参考函数对象。它可以让你引用传递给周围的一些日后调用的函数。

fish_food（）（带括号）是一个函数调用前pression，这导致被执行的功能。该函数code进行评估并运行任意返回一个值。

通过您所提供的AJAX code（以及所有异步的JavaScript涉及回调）要使用 fish_food （不带括号）。这传递了AJAX codeA引用你的成功的功能，异步执行，一旦AJAX code已经完成了往返于服务器和背部。

if I have a function defined earlier, do I need to include parenthesis when specifying that it should be used for a success callback?

what would be the difference if I did?

as in

function fish_food(){//do something}

$.ajax({
    url: '/',
    success: fish_food
});

or

$.ajax({
    url: '/',
    success: fish_food()
});

fish_food on its own (without parens) acts as a reference to the function object. It allows you to pass the reference to the function around to be invoked at some later date.

fish_food() (with parens) is a function invocation expression, which causes the function to be executed. The function code is evaluated and run with a value optionally being returned.

With the AJAX code you supplied (and all async JavaScript involving callbacks) you want to use the fish_food version (without parens). This passes the AJAX code a reference to your success function, to be executed asynchronously once the AJAX code has completed its round trip to the server and back.