blocks|key|3248349|text|你在那里得到的是一个闭包。创建并分配给handler的函数保留对me对象的引用。这是正常的、日常的JavaScript，这也是闭包通常的工作方式。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3248350|entityMap^0|J|7|W|2|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

What you have there is a closure. The function that is created and assigned to <code>handler</code> keeps a reference to the <code>me</code> object. This is normal, everyday JavaScript, and that's the way that closures work generally.

blocks|key|407302|text|您可以使用".bind()"：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|407303|var+handler+=+function()+{+this.progress();+}.bind(this);|code-block|syntax|javascript|407304|新的浏览器有"bind()"，而Mozilla+docs有一个可靠的实现，你可以用它来修补旧的浏览器。|offset|length|407305|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/bind^0|0|0|G|C|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

You can use ".bind()":

<pre><code>var handler = function() { this.progress(); }.bind(this);
</code></pre>

New browsers have "bind()", and the <a href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/bind" rel="noreferrer">Mozilla docs</a> have a solid implementation you can use to patch older browsers.

blocks|key|407321|text|原因|type|unstyled|depth|inlineStyleRanges|entityRanges|data|407322|var+handler+=+(function(o)+{+o.progress();})(this));|code-block|syntax|javascript|407323|不起作用，因为它只是立即调用anon函数，因此立即调用o.progress()并将anon函数(未定义)的返回值分配给handler。您需要从外部函数返回一个实际的函数：|offset|length|style|CODE|407324|handler+=+(function(me){
++++return+function(){
++++++++return+me.progress();
++++}
}(this));|407325|另一方面，这与变量赋值一样糟糕，看起来也一样糟糕(但仍然很有用，特别是如果这需要在循环中完成，使用更改的i而不是固定的this)。|407326|407327|顺便说一句，如果进度函数内部没有任何对this的调用，那么只执行handler+=+this.progress+(不带括号)可能就足够了。|407328|entityMap^0|0|0|R|C|1N|7|0|0|0|0|J|4|W|N|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]]|$1|G|3|H|5|6|7|X|8|@$I|Y|J|Z|K|L]|$I|10|J|11|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|12|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|13|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|14|8|@]|9|@]|A|$]]|$1|R|3|S|5|6|7|15|8|@$I|16|J|17|K|L]|$I|18|J|19|K|L]]|9|@]|A|$]]|$1|T|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]]|U|$]]

The reason

<pre><code>var handler = (function(o) { o.progress();})(this));
</code></pre>

doesn't work because it just immediately calls the anon function, therefore immediately calling <code>o.progress()</code> and assigns the return value of the anon function (undefined) to <code>handler</code>. You need to return an actual function from the outer function:

<pre><code>handler = (function(me){
 return function(){
 return me.progress();
 }
}(this));
</code></pre>

On the flip side this is equivalent and just as bad looking as bad looking as the variable assignment (but can still be useful, particularly if this needs to be done in a loop, with the changing i rather than the fixed this).

<hr>

BTW, if the progress function doesn't have any calls to <code>this</code> inside it , just doing <code>handler = this.progress</code> (without the parens) might suffice.

blocks|key|410846|text|你有没有尝试过像这样返回函数？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|410847|var+handler+=+function(o){
+++return+function(){
++++++o.progress();
+++}
}(me);|code-block|syntax|javascript|410848|现在您可以调用：|410849|handler();|410850|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Have you tried to return the function like this?

<pre><code>var handler = function(o){
 return function(){
 o.progress();
 }
}(me);
</code></pre>

Now you can call:

<pre><code>handler();
</code></pre>

blocks|key|3248575|text|匿名函数可以访问me，因为它是在外部函数(+toggle函数)内部声明的；它被外部函数关闭。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3248576|您的handler函数将由setInterval调用，它传递的参数恰好为零。这意味着您不能在处理函数本身中使用参数。|3248577|如果你真的想显式地传递me，你可以编写一个接受参数的函数，并让该函数返回一个没有参数的匿名函数，但它可以访问创建者函数的参数：|3248578|toggle:+function()+{
++++var+me+=+this;
++++var+handler+=+(function+(o)+{+return+function()+{+o.progress()+};+})(me);
++++me.intervalId+=+setInterval(handler,+me.intervalTime);
++++//...More+code
}|code-block|syntax|javascript|3248579|但这基本上增加了一层重定向，并没有真正使其更易读。除非你把这个创建函数拉到外面：|3248580|function+createProgressHandler(o)+{
++++return+function()+{
++++++++o.progress();
++++};
}

//+...

toggle:+function()+{
++++var+me+=+this;
++++var+handler+=+createProgressHandler(me);
++++me.intervalId+=+setInterval(handler,+me.intervalTime);
++++//...More+code
}|3248581|entityMap^0|8|2|M|6|0|2|7|D|B|0|B|2|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@$9|10|A|11|B|C]|$9|12|A|13|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|J|3|K|5|L|7|17|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|18|8|@]|D|@]|E|$]]|$1|Q|3|R|5|L|7|19|8|@]|D|@]|E|$M|N]]|$1|S|3|-4|5|6|7|1A|8|@]|D|@]|E|$]]]|T|$]]

The anonymous function has access to <code>me</code> because it is declared inside of the outer function (the <code>toggle</code> function); it is closed over by the outer function.

Your <code>handler</code> function will be called by <code>setInterval</code>, which passes exactly zero arguments. This means you can't use parameters in the handler function itself.

I you really want to pass <code>me</code> explicitly, you could write a function accepting an parameter, and have that function return an anonymous function without parameters, but which could access the creator function's parameter:

<pre><code>toggle: function() {
 var me = this;
 var handler = (function (o) { return function() { o.progress() }; })(me);
 me.intervalId = setInterval(handler, me.intervalTime);
 //...More code
}
</code></pre>

But this basically adds a layer of redirection without really making it more legible. Unless you pull that creating function outside:

<pre><code>function createProgressHandler(o) {
 return function() {
 o.progress();
 };
}

// ...

toggle: function() {
 var me = this;
 var handler = createProgressHandler(me);
 me.intervalId = setInterval(handler, me.intervalTime);
 //...More code
}
</code></pre>

I have some javascript code (within an object) :

<pre><code>toggle: function() {
 var me = this;
 var handler = function() { me.progress() };
 me.intervalId = setInterval(handler, me.intervalTime);
 //...More code
}
</code></pre>

I'm kind of new to javascript, so doing the above as far as I can tell actually passes the <code>me</code> variable into anonymous the function. I was wanting to see if there is a more declarative way to do so? I wanted something along the line of:

<pre><code>var handler = (function(o) { o.progress();})(this));
</code></pre>

but that doesn't seem to be working... Am I missing something? Is this a case where "this is the way the language works so just declare a local variable and deal with it"?

UPDATE:

The source to my problem was/is my unclear understanding of scope and closures in javascript. I found <a href="http://odetocode.com/blogs/scott/archive/2007/07/05/function-apply-and-function-call-in-javascript.aspx">this article</a> to help me understand a little more.

javascript anonymous function parameter passing

我有一些javascript代码(在一个对象中)：toggle: function() {    var me = this;    var handler = function() { me.progress() };    me.intervalId = setInterval(handler, me.interv...

问javascript匿名函数参数传递
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