blocks|key|250240|text|返回不带()的函数名将返回对该函数的引用，可以像使用var+s+=+a()一样进行赋值。s现在包含对函数b()的引用，调用s()在功能上等同于调用b()。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|250241|//+Return+a+reference+to+the+function+b().
//+In+your+example,+the+reference+is+assigned+to+var+s
return+b;|code-block|syntax|javascript|250242|在return语句中使用()调用函数将执行该函数，并返回该函数返回的任何值。它类似于调用var+x+=+b();，但不是分配b()的返回值，而是从调用函数a()返回返回值。如果函数b()本身没有返回值，则在b()完成任何其他工作后，该调用将返回undefined。|250243|//+Execute+function+b()+and+return+its+value
return+b();
//+If+b()+has+no+return+value,+this+is+equivalent+to+calling+b(),+followed+by
//+return+undefined;|250244|entityMap^0|4|2|Q|B|18|1|1G|3|1P|3|21|3|0|0|C|2|18|C|1Q|3|25|3|2I|3|2V|3|3E|9|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|13|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|14|8|@$9|15|A|16|B|C]|$9|17|A|18|B|C]|$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]|$9|1D|A|1E|B|C]|$9|1F|A|1G|B|C]|$9|1H|A|1I|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|1J|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|1K|8|@]|D|@]|E|$]]]|P|$]]

<p>Returning the function name without <code>()</code> returns a reference to the function, which can be assigned as you've done with <code>var s = a()</code>. <code>s</code> now contains a reference to the function <code>b()</code>, and calling <code>s()</code> is functionally equivalent to calling <code>b()</code>.</p>

<pre><code>// Return a reference to the function b().
// In your example, the reference is assigned to var s
return b;
</code></pre>

<p>Calling the function with <code>()</code> in a return statement executes the function, and returns whatever value was returned by the function.  It is similar to calling <code>var x = b();</code>, but instead of assigning the return value of <code>b()</code> you are returning it from the calling function <code>a()</code>.  If the function <code>b()</code> itself does not return a value, the call returns <code>undefined</code> after whatever other work is done by <code>b()</code>.</p>

<pre><code>// Execute function b() and return its value
return b();
// If b() has no return value, this is equivalent to calling b(), followed by
// return undefined;
</code></pre>


blocks|key|2933575|text|当您返回b时，它只是对函数b的引用，而不是在此时执行。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2933576|当您返回b()时，您正在执行函数并返回它的值。|2933577|在您的示例中尝试使用alerting+typeof(s)。代码片段b将为您提供“函数”。snippet+a会给你带来什么？|2933578|entityMap^0|4|1|0|4|3|0|A|5|J|9|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|K|$]]

<p>When you return <code>b</code>, it is just a reference to function b, but not being executed at this time.</p>

<p>When you return <code>b()</code>, you're executing the function and returning its value.</p>

<p>Try <code>alert</code>ing <code>typeof(s)</code> in your examples. Snippet b will give you 'function'. What will snippet a give you?</p>


blocks|key|250253|text|return+b();调用函数b()并返回其结果。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|250254|return+b;返回对函数b的引用，您可以将其存储在一个变量中，以便稍后调用。|250255|entityMap^0|0|B|0|0|9|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|P|8|@]|D|@]|E|$]]]|I|$]]

<p><code>return b();</code> calls the function b(), and returns its result.</p>

<p><code>return b;</code> returns a reference to the function b, which you can store in a variable to call later.</p>


blocks|key|2933624|text|返回b就是返回一个函数对象。在Javascript中，函数就是对象，就像任何其他对象一样。如果你觉得这没什么用，就把"object“替换成"thing”。您可以从函数返回任何对象。您可以返回true/false值。一个整数(1,2,3,4...)。你可以返回一个字符串。您可以返回具有多个属性的复杂对象。你可以返回一个函数。一个函数只是一个东西。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2933625|在你的例子中，返回b会返回事物，事物是一个可调用的函数。返回b()将返回可调用函数返回的值。|2933626|考虑下面的代码：|2933627|function+b()+{
+++return+42;
}|code-block|syntax|javascript|2933628|使用上面的定义，return+b();返回值42。另一方面，return+b;返回一个函数，该函数本身返回值42。这是两件不同的事情。|2933629|entityMap^0|2|1|0|9|1|U|3|0|0|0|8|B|U|9|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|10|8|@]|D|@]|E|$]]|$1|J|3|K|5|L|7|11|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|12|8|@$9|13|A|14|B|C]|$9|15|A|16|B|C]]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|17|8|@]|D|@]|E|$]]]|R|$]]

<p>Returning <code>b</code> is returning a function object.  In Javascript, functions are just objects, like any other object.  If you find that not helpful, just replace the word "object" with "thing".  You can return any object from a function.  You can return a true/false value. An integer (1,2,3,4...).  You can return  a string.  You can return a complex object with multiple properties.  And you can return a function.  a function is just a thing. </p>

<p>In your case, returning <code>b</code> returns the thing, the thing is a callable function. Returning <code>b()</code> returns the value returned by the callable function.  </p>

<p>Consider this code:</p>

<pre><code>function b() {
   return 42;
}
</code></pre>

<p>Using the above definition, <code>return b();</code> returns the value 42.  On the other hand <code>return b;</code> returns a function, that itself returns the value of 42.  They are two different things. </p>


blocks|key|252003|text|把函数想象成一个类型，就像int一样。您可以在函数中返回in。你也可以返回函数，它们是"function“类型的对象。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|252004|现在的语法问题:因为函数返回值，你怎么能返回一个函数而不是返回值呢？|252005|通过省略括号！因为没有括号，函数将不会被执行！所以：|252006|return+b;|code-block|syntax|javascript|252007|将返回"function“(假设您返回的是一个数字)，而：|252008|return+b();|252009|首先执行函数，然后返回执行它所获得的值，这是很大的区别！|offset|length|style|BOLD|252010|entityMap^0|0|0|0|0|0|0|6|3|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Y|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|Z|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|10|8|@]|9|@]|A|$]]|$1|M|3|N|5|H|7|11|8|@]|9|@]|A|$I|J]]|$1|O|3|P|5|6|7|12|8|@$Q|13|R|14|S|T]]|9|@]|A|$]]|$1|U|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|V|$]]

<p>Imagine the function as a type, like an int. You can return ints in a function.
You can return functions too, they are object of type "function".</p>

<p>Now the syntax problem: because functions returns values, how can you return a function and not it's returning value?</p>

<p>by omitting brackets! Because without brackets, the function won't be executed! So:</p>

<pre><code>return b;
</code></pre>

<p>Will return the "function" (imagine it like if you are returning a number), while:</p>

<pre><code>return b();
</code></pre>

<p>First executes the function <strong>then</strong> return the value obtained by executing it, it's a big difference!</p>


blocks|key|255316|text|创建变量|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|255317|var+thing1+=+undefined;|code-block|syntax|javascript|255318|声明函数|255319|function+something1+()+{
++++return+"Hi+there,+I'm+number+1!";
}|255320|警告thing1+(我们的第一个变量)的值：|CODE|255321|alert(thing1);+//+Outputs:+"undefined".|255322|现在，如果我们希望thing1成为函数something1的引用，这意味着它将与我们创建的函数相同，我们将这样做：|255323|thing1+=+something1;|255324|然而，如果我们想要函数的return+值，那么我们必须将它赋值为已执行函数的返回值。您可以使用括号执行该函数：|255325|thing1+=+something1();+//+Value+of+thing1:+"Hi+there,+I'm+number+1!"+|255326|entityMap^0|2|2|0|0|2|2|0|0|2|6|K|1|0|0|9|6|J|A|U|2|0|0|C|6|J|1|0|0^^$0|@$1|2|3|4|5|6|7|13|8|@$9|14|A|15|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|16|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|17|8|@$9|18|A|19|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|1A|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|1B|8|@$9|1C|A|1D|B|Q]|$9|1E|A|1F|B|C]]|D|@]|E|$]]|$1|R|3|S|5|H|7|1G|8|@]|D|@]|E|$I|J]]|$1|T|3|U|5|6|7|1H|8|@$9|1I|A|1J|B|Q]|$9|1K|A|1L|B|Q]|$9|1M|A|1N|B|C]]|D|@]|E|$]]|$1|V|3|W|5|H|7|1O|8|@]|D|@]|E|$I|J]]|$1|X|3|Y|5|6|7|1P|8|@$9|1Q|A|1R|B|Q]|$9|1S|A|1T|B|C]]|D|@]|E|$]]|$1|Z|3|10|5|H|7|1U|8|@]|D|@]|E|$I|J]]|$1|11|3|-4|5|6|7|1V|8|@]|D|@]|E|$]]]|12|$]]

<p>Create a <strong>variable</strong>:</p>

<pre><code>var thing1 = undefined;
</code></pre>

<p>Declare a <strong>Function</strong>:</p>

<pre><code>function something1 () {
    return "Hi there, I'm number 1!";
}
</code></pre>

<p>Alert the <strong>value</strong> of <code>thing1</code> (our first variable):</p>

<pre><code>alert(thing1); // Outputs: "undefined".
</code></pre>

<p>Now, if we wanted <code>thing1</code> to be a <strong>reference</strong> to the function <code>something1</code>, meaning it would be the same thing as our created function, we would do:</p>

<pre><code>thing1 = something1;
</code></pre>

<p>However, if we wanted the <code>return</code> <strong>value</strong> of the function then we must assign it the return value of the executed function. You execute the function by using parenthesis:</p>

<pre><code>thing1 = something1(); // Value of thing1: "Hi there, I'm number 1!" 
</code></pre>


blocks|key|2933784|text|将变量赋给函数(不带括号)会复制对该函数的引用。将括号放在函数名的末尾，调用函数，返回函数返回值。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2933785|Demo|offset|length|2933786|​|2933787|function+a()+{
++alert('A');
}
//alerts+'A',+returns+undefined

function+b()+{
++alert('B');
++return+a;
}
//alerts+'B',+returns+function+a

function+c()+{
++alert('C');
++return+a();
}
//alerts+'C',+alerts+'A',+returns+undefined

alert("Function+'a'+returns+"+%2B+a());
alert("Function+'b'+returns+"+%2B+b());
alert("Function+'c'+returns+"+%2B+c());|code-block|syntax|javascript|2933788|2933789|在您的示例中，您还将在函数中定义函数。例如：|2933790|2933791|function+d()+{
++function+e()+{
++++alert('E');
++}
++return+e;
}
d()();
//alerts+'E'|2933792|2933793|该函数仍然是可调用的。它仍然存在。这在JavaScript中一直都在使用。函数可以像其他值一样传递。请考虑以下几点：|2933794|2933795|function+counter()+{
++var+count+=+0;
++return+function()+{
++++alert(count%2B%2B);
++}
}
var+count+=+counter();
count();
count();
count();|2933796|2933797|函数count可以保留在其外部定义的变量。这称为闭包。它在JavaScript中也被大量使用。|2933798|entityMap|0|LINK|mutability|MUTABLE|url|http://jsfiddle.net/kaleb/Las6w/^0|0|0|4|0|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|19|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1A|8|@]|9|@$D|1B|E|1C|1|1D]]|A|$]]|$1|F|3|G|5|6|7|1E|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|1F|8|@]|9|@]|A|$K|L]]|$1|M|3|G|5|6|7|1G|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|1H|8|@]|9|@]|A|$]]|$1|P|3|G|5|6|7|1I|8|@]|9|@]|A|$]]|$1|Q|3|R|5|J|7|1J|8|@]|9|@]|A|$K|L]]|$1|S|3|G|5|6|7|1K|8|@]|9|@]|A|$]]|$1|T|3|U|5|6|7|1L|8|@]|9|@]|A|$]]|$1|V|3|G|5|6|7|1M|8|@]|9|@]|A|$]]|$1|W|3|X|5|J|7|1N|8|@]|9|@]|A|$K|L]]|$1|Y|3|G|5|6|7|1O|8|@]|9|@]|A|$]]|$1|Z|3|10|5|6|7|1P|8|@]|9|@]|A|$]]|$1|11|3|-4|5|6|7|1Q|8|@]|9|@]|A|$]]]|12|$13|$5|14|15|16|A|$17|18]]]]

<p>Assigning a variable to a function (without the parenthesis) copies the reference to the function. Putting the parenthesis at the end of a function name, calls the function, returning the functions return value.</p>
<h2><a href="http://jsfiddle.net/kaleb/Las6w/" rel="noreferrer">Demo</a></h2>
<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>function a() {
  alert('A');
}
//alerts 'A', returns undefined

function b() {
  alert('B');
  return a;
}
//alerts 'B', returns function a

function c() {
  alert('C');
  return a();
}
//alerts 'C', alerts 'A', returns undefined

alert("Function 'a' returns " + a());
alert("Function 'b' returns " + b());
alert("Function 'c' returns " + c());</code></pre>
</div>
</div>
</p>
<p>In your example, you are also defining functions within a function. Such as:</p>
<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>function d() {
  function e() {
    alert('E');
  }
  return e;
}
d()();
//alerts 'E'</code></pre>
</div>
</div>
</p>
<p>The function is still callable. It still exists. This is used in JavaScript all the time. Functions can be passed around <em>just</em> like other values. Consider the following:</p>
<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>function counter() {
  var count = 0;
  return function() {
    alert(count++);
  }
}
var count = counter();
count();
count();
count();</code></pre>
</div>
</div>
</p>
<p>The function count can keep the variables that were defined outside of it. This is called a closure. It's also used a lot in JavaScript.</p>


blocks|key|252047|text|代码片段一：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|252048|function+a()+{
++
++++alert('A!');

++++function+b(){
++++++++alert('B!');+
++++}

++++return+b();+//return+nothing+here+as+b+not+defined+a+return+value
}

var+s+=+a();+//s+got+nothing+assigned+as+b()+and+thus+a()+return+nothing.
alert('break');
s();+//+s+equals+nothing+so+nothing+will+be+executed,+JavaScript+interpreter+will+complain|code-block|syntax|javascript|252049|语句'b()‘表示执行名为'b’的函数，该函数显示一个带有文本'B!‘的对话框。|252050|语句'return+b();‘表示执行名为'b’的函数，然后返回函数'b‘返回的内容。但是'b‘不返回任何内容，那么'return+b()’语句也不返回任何内容。如果b()返回一个数字，那么‘return+b()’也是一个数字。|252051|现在's‘被赋值为'a()’返回的值，返回'b()'，即nothing，所以‘s’什么都不是(在JavaScript中，它实际上是一个'undefined‘。因此，当您要求JavaScript解释“%25s”是什么数据类型时，JavaScript解释器会告诉您“%25s”是未定义的。)因为's‘是一个未定义的，当你要求JavaScript执行这个语句's()’的时候，你是在要求JavaScript执行一个名为's‘的函数，但是's’这里是一个‘未定义的’，而不是一个函数，所以JavaScript会抱怨，“嘿，s不是一个函数，我不知道如何处理这个s"，然后JavaScript会显示”未捕获的TypeError:+s不是函数“的错误消息(在火狐和Chrome中测试过)|252052|252053|代码段二|252054|function+a()+{
++
++++alert('A!');

++++function+b(){
++++++++alert('B!');+
++++}

++++return+b;+//return+pointer+to+function+b+here
}

var+s+=+a();++//s+get+the+value+of+pointer+to+b
alert('break');
s();+//+b()+function+is+executed|252055|现在，函数'a‘返回一个指向名为'b’的函数的指针/别名。因此，当执行's=a()‘时，'s’将得到一个指向b的值，即's‘现在是'b’的别名，调用's‘等于调用'b’。即“%25s”现在是一个函数。Execute+'s()‘表示运行函数'b’(与执行‘b()’相同)，一个显示'B!‘的对话框。将出现(即在函数‘b’中运行'alert('B!')；语句)|252056|entityMap^0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|W|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|X|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|Y|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|Z|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|10|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|11|8|@]|9|@]|A|$]]|$1|P|3|Q|5|D|7|12|8|@]|9|@]|A|$E|F]]|$1|R|3|S|5|6|7|13|8|@]|9|@]|A|$]]|$1|T|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|U|$]]

<p>Snippet one:</p>
<pre class="lang-js prettyprint-override"><code>function a() {
  
    alert('A!');

    function b(){
        alert('B!'); 
    }

    return b(); //return nothing here as b not defined a return value
}

var s = a(); //s got nothing assigned as b() and thus a() return nothing.
alert('break');
s(); // s equals nothing so nothing will be executed, JavaScript interpreter will complain
</code></pre>
<p>the statement 'b()' means to execute the function named 'b' which shows a dialog box with text 'B!'</p>
<p>the statement 'return b();' means to execute a function named 'b' and then return what function 'b' return. but 'b' returns nothing, then this statement 'return b()' returns nothing either.
If b() return a number, then ‘return b()’ is a number too.</p>
<p>Now ‘s’ is assigned the value of what 'a()' return, which returns 'b()', which is nothing, so 's' is nothing (in JavaScript it’s a thing actually, it's an 'undefined'. So when you ask JavaScript to interpret what data type the 's' is, JavaScript interpreter will tell you 's' is an undefined.) As 's' is an undefined, when you ask JavaScript to execute this statement 's()', you're asking JavaScript to execute a function named as 's', but 's' here is an 'undefined', not a function, so JavaScript will complain, &quot;hey, s is not a function, I don't know how to do with this s&quot;, then a &quot;Uncaught TypeError: s is not a function&quot; error message will be shown by JavaScript (tested in Firefox and Chrome)</p>
<hr />
<p>Snippet Two</p>
<pre class="lang-js prettyprint-override"><code>function a() {
  
    alert('A!');

    function b(){
        alert('B!'); 
    }

    return b; //return pointer to function b here
}

var s = a();  //s get the value of pointer to b
alert('break');
s(); // b() function is executed
</code></pre>
<p>now, function 'a' returning a pointer/alias to a function named 'b'. so when execute 's=a()', 's' will get a value pointing to b, i.e. 's' is an alias of 'b' now, calling 's' equals calling 'b'. i.e. 's' is a function now.  Execute 's()' means to run function 'b' (same as executing 'b()'), a dialog box showing 'B!' will appeared (i.e. running the 'alert('B!'); statement in the function 'b')</p>


blocks|key|255354|text|这里有一个很好的例子来展示它是如何在实践中工作的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|255355|当您使用两个参数调用并返回结果时|255356|function+sum(x,+y)+{
if+(y+!==+undefined)+{
+++return+x+%2B+y;
++}+else+{
++++return+function(y)+{+return+x+%2B+y;+};
+}
}

console.log(sum(3)(8))|code-block|syntax|javascript|255357|还有另一种方法使用访问js中的参数：|255358|function+sum(x)+{
+if+(arguments.length+==+2)+{
++++return+arguments[0]+%2B+arguments[1];
+}+else+{
+++return+function(y)+{+return+x+%2B+y;+};
+}
+}|255359|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

<p>Here is a nice example to show how its work in practice:</p>
<p>when you call in with two parameter and returns a result</p>
<pre><code>function sum(x, y) {
if (y !== undefined) {
   return x + y;
  } else {
    return function(y) { return x + y; };
 }
}

console.log(sum(3)(8))
</code></pre>
<p>there is also another way using the accessing to the arguments in js:</p>
<pre><code>function sum(x) {
 if (arguments.length == 2) {
    return arguments[0] + arguments[1];
 } else {
   return function(y) { return x + y; };
 }
 }
</code></pre>


blocks|key|254121|text|让我们通过两个具有相同输出的示例来尝试理解"return“概念，一个不使用"return”概念，另一个使用"return“概念，两者都给出了相同的结果。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|254122|​|254123|let+myLuckyNumber+=+22
function+addsToMyLuckyNumber(incrementBy,+multiplyBy)+{
++++myLuckyNumber+=+(myLuckyNumber+%2B+incrementBy)+*+multiplyBy
}
addsToMyLuckyNumber(5,+2)

console.log(myLuckyNumber)|code-block|syntax|javascript|254124|254125|254126|const+myLuckyNumber+=+22
function+addsToMyLuckyNumber(incrementBy,+multiplyBy)+{
++++return+(myLuckyNumber+%2B+incrementBy)+*+multiplyBy
}
myNewLuckyNumber+=+addsToMyLuckyNumber(5,2)

console.log(myLuckyNumber,+myNewLuckyNumber)|254127|在第一个代码片段中，您可以看到代码|254128|254129|myLuckyNumber+=+(myLuckyNumber+%2B+incrementBy)+*+multiplyBy|254130|您不能将类似的代码赋给第二个代码片段，因为它将不起作用，所以我们使用"return“概念并分配一个新的变量。|254131|function+addsToMyLuckyNumber(incrementBy,+multiplyBy)+{
++++return+(myLuckyNumber+%2B+incrementBy)+*+multiplyBy
}
myNewLuckyNumber+=+addsToMyLuckyNumber(5,2)|254132|entityMap^0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Y|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Z|8|@]|9|@]|A|$G|H]]|$1|I|3|C|5|6|7|10|8|@]|9|@]|A|$]]|$1|J|3|C|5|6|7|11|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|12|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|13|8|@]|9|@]|A|$]]|$1|O|3|C|5|6|7|14|8|@]|9|@]|A|$]]|$1|P|3|Q|5|F|7|15|8|@]|9|@]|A|$G|H]]|$1|R|3|S|5|6|7|16|8|@]|9|@]|A|$]]|$1|T|3|U|5|F|7|17|8|@]|9|@]|A|$G|H]]|$1|V|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|W|$]]

<h2>Let's try to understand the &quot;return&quot; concept with two examples with the same output, one without using the &quot;return&quot; concept and the other with the &quot;return&quot; concept, both giving the same outcome.</h2>
<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>let myLuckyNumber = 22
function addsToMyLuckyNumber(incrementBy, multiplyBy) {
    myLuckyNumber = (myLuckyNumber + incrementBy) * multiplyBy
}
addsToMyLuckyNumber(5, 2)

console.log(myLuckyNumber)</code></pre>
</div>
</div>
</p>
<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>const myLuckyNumber = 22
function addsToMyLuckyNumber(incrementBy, multiplyBy) {
    return (myLuckyNumber + incrementBy) * multiplyBy
}
myNewLuckyNumber = addsToMyLuckyNumber(5,2)

console.log(myLuckyNumber, myNewLuckyNumber)</code></pre>
</div>
</div>

In the first snippet, you can see the code</p>
<pre><code>myLuckyNumber = (myLuckyNumber + incrementBy) * multiplyBy
</code></pre>
<p>you cannot assign a similar code to the second snippet, since it will not work, so we use &quot;return&quot; concept and assign a new variable.</p>
<pre><code>function addsToMyLuckyNumber(incrementBy, multiplyBy) {
    return (myLuckyNumber + incrementBy) * multiplyBy
}
myNewLuckyNumber = addsToMyLuckyNumber(5,2)
</code></pre>


<p>I'm stuck with this concept of 'Functions that return functions'. I'm referring the book 'Object Oriented Javascript' by Stoyan Stefanov.</p>

<p><strong>Snippet One:</strong>  </p>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>    function a() {
      
        alert('A!');
    
        function b(){
            alert('B!'); 
        }
    
        return b();
    }
    
    var s = a();
    alert('break');
    s();</code></pre>
</div>
</div>
</p>

<p><strong>Output:</strong></p>

<pre><code>A!
B!
break
</code></pre>

<p><strong>Snippet Two</strong></p>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>function a() {
  
    alert('A!');

    function b(){
        alert('B!'); 
    }

    return b;
}

var s = a();
alert('break');
s();</code></pre>
</div>
</div>

<strong>Output:</strong></p>

<pre><code>A!
break
B!
</code></pre>

<p>Can someone please tell me the difference between returning <code>b</code> and <code>b()</code> in the above snippets?</p>


Functions that return a function

解释器

我坚持“返回函数的函数”这个概念。我指的是Stoyan Stefanov的书“面向对象的Javascript”。代码片段一：​    function a() {              alert('A!');            function b(){            alert('B!');    ...

问返回函数的函数
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