这样做的好处（称为“命名函数表达式”）是函数有一个实际的名称。在你的第二个版本中，property有名称，但函数没有。为函数提供实际名称可以帮助您的工具为您提供帮助（调用堆栈列表、断点列表等）更多：匿名者匿名者 http://blog.niftysnippets.org/2010/03/anonymouses-anonymous.html
The 坏处其原因是，它在一些损坏的 JavaScript 引擎中会产生意想不到的结果，例如 IE8 及更早版本中的引擎。在 IE8 及更早版本中，Paul Irish 的版本创建两个完全不同时间的两个独立功能 http://blog.niftysnippets.org/2010/09/double-take.html。但这并不是真正的问题，除非您保留并使用对它们的引用，并期望它们是相同的函数（例如，在挂接和取消挂接事件处理程序时）。鉴于是保罗，我猜他肯定不会这样做。
回复你的问题标题：请注意，它是not一个函数宣言，但你这样认为是可以原谅的，因为它看起来几乎一模一样。 :-) 这是一个函数表达。函数声明和函数表达式发生在完全不同的时间，并且对它们创建的范围有不同的影响。
只是为了完整性：
// This is a function declaration -- note that it's not a "right-hand
// value", e.g., we're not using the result of it immediately (via an
// assignment, a property initializer, calling it, or passing it into
// a function as an argument -- none of those).
//
// Declarations happen upon entry to the scope (not as part of step-by-
// step code). The function's name is added to the scope in which it's
// declared. Declarations are illegal inside branches (`if`, `try/catch`,
// `for`, etc.), but some engines will rewrite them as expressions for
// you if you do that. Others will not, they'll just always declare the
// function regardless of whether the code was reached. So don't do that.
function foo() {
}
// These are all anonymous function expressions. The function in the
// expression has no name, although some debuggers are pretty smart
// about looking at the expression and (where they can) listing a
// kind of pseudo-name for the function. Others are not that smart,
// which is why I avoid anonymous functions.
//
// Expressions happen when they're reached in step-by-step code.
var f = function() { };
var obj = {
prop: function() { }
};
doSomethingCoolWithAFunction(function() { });
(function() { })(); // Call it immediately
!function() { }(); // Call it immediately
~function() { }(); // Call it immediately, there are a few variants
// These are all *named* function expressions.
//
// Since they're expressions, they happen when they're reached in the
// step-by-step code. The function's name is NOT added to the containing
// scope (except by engines with bugs).
//
// These are the same examples as above, but with a name. No other changes.
var f = function foo() { };
var obj = {
prop: function foo() { }
};
doSomethingCoolWithAFunction(function foo() { });
(function foo() { })(); // Call it immediately
!function foo() { }(); // Call it immediately
~function foo() { }(); // Call it immediately, there are a few variants
