Javascript 有返回语句和没有返回语句的函数之间有区别吗？

假设有两个相同的函数不返回值

function a() {
    // do some interesting things
}

function b() {
    // do the same interesting things
    return;
}

---

函数

b

显然更详细，但它们之间有什么函数上的区别吗？

没有真正的区别；两者都将返回未定义的

没有return语句的函数将返回

未定义的
，带有空
return
语句的函数也是如此


要自己确认这一点，您可以运行以下代码--：

通常，您返回的是一个值。那么比如说,

function b() {
  return 'hello';
}

a = b();

console.log(a);

将向您的控制台输出“hello”。
Adam是正确的；这两个函数都返回未定义的值，如果您不关心返回值（或希望该值未定义），则任何一种方法都是完全正确的。然而，在更复杂的程序中，从函数显式返回通常更好，特别是因为Javascript程序通常具有复杂的回调机制。例如，在这段代码中（比您的代码稍微复杂一点），我相信return语句确实有助于澄清代码：

function someAsyncFunction(someVar, callback) {
    // do something, and then...
    callback(someVar);
    // will return undefined
    return;
}

function c(){
    var someState = null;
    if (some condition) {
        return someAsyncFunction(some variable, function () {
            return "from the callback but not the function";
        });
        // we've passed the thread of execution to someAsyncFunction
        // and explicitly returned from function c.  If this line
        // contained code, it would not be executed.
    } else if (some other condition) {
         someState = "some other condition satisfied";
    } else {
         someState = "no condition satisfied";
    }
    // Note that if you didn't return explicitly after calling
    // someAsyncFunction you would end up calling doSomethingWith(null)
    // here.  There are obviously ways you could avoid this problem by
    // structuring your code differently, but explicit returns really help
    // avoid silly mistakes like this which can creep into complex programs.
    doSomethingWith(someState);
    return;
}

// Note that we don't care about the return value.
c();

一个好的答案应该包括一个指向ECMA规范返回相关部分的链接；这里基本上是指终止函数。因此，如果你把它作为你函数的最后一部分，它不会做任何有用的事情。规范中的12.9，对那些感兴趣的人来说。完全主观，但我完全不同意。我不认为这会使代码更容易阅读。相反，它是不必要的，所以它只会造成混乱。我的2c。我想每个人都有自己的。
function someAsyncFunction(someVar, callback) {
    // do something, and then...
    callback(someVar);
    // will return undefined
    return;
}

function c(){
    var someState = null;
    if (some condition) {
        return someAsyncFunction(some variable, function () {
            return "from the callback but not the function";
        });
        // we've passed the thread of execution to someAsyncFunction
        // and explicitly returned from function c.  If this line
        // contained code, it would not be executed.
    } else if (some other condition) {
         someState = "some other condition satisfied";
    } else {
         someState = "no condition satisfied";
    }
    // Note that if you didn't return explicitly after calling
    // someAsyncFunction you would end up calling doSomethingWith(null)
    // here.  There are obviously ways you could avoid this problem by
    // structuring your code differently, but explicit returns really help
    // avoid silly mistakes like this which can creep into complex programs.
    doSomethingWith(someState);
    return;
}

// Note that we don't care about the return value.
c();