blocks|key|248322|text|UnderscoreJs有一个函数可以做到这一点，underscorejs.org/#once|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|248323|++//+Returns+a+function+that+will+be+executed+at+most+one+time,+no+matter+how
++//+often+you+call+it.+Useful+for+lazy+initialization.
++_.once+=+function(func)+{
++++var+ran+=+false,+memo;
++++return+function()+{
++++++if+(ran)+return+memo;
++++++ran+=+true;
++++++memo+=+func.apply(this,+arguments);
++++++func+=+null;
++++++return+memo;
++++};
++};|code-block|syntax|javascript|248324|entityMap|0|LINK|mutability|MUTABLE|url|http://underscorejs.org/#once^0|P|M|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

UnderscoreJs has a function that does that, <a href="http://underscorejs.org/#once">underscorejs.org/#once</a>

<pre><code> // Returns a function that will be executed at most one time, no matter how
 // often you call it. Useful for lazy initialization.
 _.once = function(func) {
 var ran = false, memo;
 return function() {
 if (ran) return memo;
 ran = true;
 memo = func.apply(this, arguments);
 func = null;
 return memo;
 };
 };
</code></pre>

blocks|key|248596|text|谈到静态变量，这有点像闭包变量：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|248597|var+once+=+function()+{
++++if(once.done)+return;
++++console.log('Doing+this+once!');
++++once.done+=+true;
};

once();+once();+|code-block|syntax|javascript|248598|然后，如果您愿意，可以重置函数：|248599|once.done+=+false;|248600|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|$]]

Talking about static variables, this is a little bit like closure variant: 

<pre><code>var once = function() {
 if(once.done) return;
 console.log('Doing this once!');
 once.done = true;
};

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

You could then reset a function if you wish: 

<pre><code>once.done = false;
</code></pre>

blocks|key|248283|text|var+quit+=+false;

function+something()+{
++++if(quit)+{
+++++++return;
++++}+
++++quit+=+true;
++++...+other+code....
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|248284|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>var quit = false;

function something() {
 if(quit) {
 return;
 } 
 quit = true;
 ... other code....
}
</code></pre>

blocks|key|248334|text|尝尝这个|type|unstyled|depth|inlineStyleRanges|entityRanges|data|248335|var+fun+=+(function()+{
++var+called+=+false;
++return+function()+{
++++if+(!called)+{
++++++console.log("I++called");
++++++called+=+true;
++++}
++}
})()|code-block|syntax|javascript|248336|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

try this 

<pre><code>var fun = (function() {
 var called = false;
 return function() {
 if (!called) {
 console.log("I called");
 called = true;
 }
 }
})()
</code></pre>

blocks|key|248342|text|一个叫克罗克福德的家伙..。:)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|248343|function+once(func)+{
++++return+function+()+{
++++++++var+f+=+func;
++++++++func+=+null;
++++++++return+f.apply(
++++++++++++this,
++++++++++++arguments
++++++++);
++++};
}|code-block|syntax|javascript|248344|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

From some dude named Crockford... :)

<pre><code>function once(func) {
 return function () {
 var f = func;
 func = null;
 return f.apply(
 this,
 arguments
 );
 };
}
</code></pre>

blocks|key|465233|text|与setInterval配合使用的可重用invalidate函数|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|465234|var+myFunc+=+function+(){
++if+(invalidate(arguments))+return;
++console.log('called+once+and+never+again!');+//+your+stuff+here
};

const+invalidate+=+function(a)+{
++var+fired+=+a.callee.fired;
++a.callee.fired+=+true;
++return+fired;
}

setInterval(myFunc,+1000);|code-block|syntax|javascript|465235|在JSBin上试试：https://jsbin.com/vicipar/edit?js,console|465236|answer+from+Bunyk的变体|465237|entityMap|0|LINK|mutability|MUTABLE|url|https://jsbin.com/vicipar/edit?js,console|1|//stackoverflow.com/a/35984663/4592648^0|1|B|K|A|0|0|A|15|0|0|0|H|1|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$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|@]|D|@$9|15|A|16|1|17]]|E|$]]|$1|M|3|N|5|6|7|18|8|@]|D|@$9|19|A|1A|1|1B]]|E|$]]|$1|O|3|-4|5|6|7|1C|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]|W|$5|R|S|T|E|$U|X]]]]

Reusable <code>invalidate</code> function which works with <code>setInterval</code>:

<pre><code>var myFunc = function (){
 if (invalidate(arguments)) return;
 console.log('called once and never again!'); // your stuff here
};

const invalidate = function(a) {
 var fired = a.callee.fired;
 a.callee.fired = true;
 return fired;
}

setInterval(myFunc, 1000);
</code></pre>

Try it on JSBin: <a href="https://jsbin.com/vicipar/edit?js,console" rel="nofollow noreferrer">https://jsbin.com/vicipar/edit?js,console</a>

Variation of <a href="//stackoverflow.com/a/35984663/4592648">answer from Bunyk</a>

blocks|key|248711|text|简单的装饰器，在你需要的时候很容易编写|type|unstyled|depth|inlineStyleRanges|entityRanges|data|248712|function+one(func)+{
++return+function+()+{
+++++func+&&+func.apply(this,+arguments);
+++++func+=+null;
++}
}|code-block|syntax|javascript|248713|使用：|248714|var+initializer=+one(+_+=>{
++++++console.log('initializing')
++})

initializer()+//+'initializing'
initializer()+//+nop
initializer()+//+nop|248715|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|$]]

simple decorator that easy to write when you need 

<pre><code>function one(func) {
 return function () {
 func &amp;&amp; func.apply(this, arguments);
 func = null;
 }
}
</code></pre>

using:

<pre><code>var initializer= one( _ =&gt;{
 console.log('initializing')
 })

initializer() // 'initializing'
initializer() // nop
initializer() // nop
</code></pre>

blocks|key|465039|text|下面是一个JSFiddle+-+http://jsfiddle.net/6yL6t/示例|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|465040|和代码：|465041|function+hashCode(str)+{
++++var+hash+=+0,+i,+chr,+len;
++++if+(str.length+==+0)+return+hash;
++++for+(i+=+0,+len+=+str.length;+i+<+len;+i%2B%2B)+{
++++++++chr+++=+str.charCodeAt(i);
++++++++hash++=+((hash+<<+5)+-+hash)+%2B+chr;
++++++++hash+%7C=+0;+//+Convert+to+32bit+integer
++++}
++++return+hash;
}

var+onceHashes+=+{};

function+once(func)+{
++++var+unique+=+hashCode(func.toString().match(/function[%5E{]%2B\{([\s\S]*)\}$/)[1]);

++++if+(!onceHashes[unique])+{
++++++++onceHashes[unique]+=+true;
++++++++func();
++++}
}|code-block|syntax|javascript|465042|你可以这样做：|465043|for+(var+i=0;+i<10;+i%2B%2B)+{
++++once(function()+{
++++++++alert(i);
++++});
}|465044|并且它只会运行一次:)|465045|entityMap|0|LINK|mutability|MUTABLE|url|http://jsfiddle.net/6yL6t/^0|G|Q|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@$A|Z|B|10|1|11]]|C|$]]|$1|D|3|E|5|6|7|12|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|13|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|14|8|@]|9|@]|C|$]]|$1|M|3|N|5|H|7|15|8|@]|9|@]|C|$I|J]]|$1|O|3|P|5|6|7|16|8|@]|9|@]|C|$]]|$1|Q|3|-4|5|6|7|17|8|@]|9|@]|C|$]]]|R|$S|$5|T|U|V|C|$W|X]]]]

Here is an example JSFiddle - <a href="http://jsfiddle.net/6yL6t/" rel="nofollow">http://jsfiddle.net/6yL6t/</a>

And the code:

<pre><code>function hashCode(str) {
 var hash = 0, i, chr, len;
 if (str.length == 0) return hash;
 for (i = 0, len = str.length; i &lt; len; i++) {
 chr = str.charCodeAt(i);
 hash = ((hash &lt;&lt; 5) - hash) + chr;
 hash |= 0; // Convert to 32bit integer
 }
 return hash;
}

var onceHashes = {};

function once(func) {
 var unique = hashCode(func.toString().match(/function[^{]+\{([\s\S]*)\}$/)[1]);

 if (!onceHashes[unique]) {
 onceHashes[unique] = true;
 func();
 }
}
</code></pre>

You could do:

<pre><code>for (var i=0; i&lt;10; i++) {
 once(function() {
 alert(i);
 });
}
</code></pre>

And it will run only once :)

blocks|key|248481|text|初始设置：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|248482|var+once+=+function(+once_fn+)+{
++++var+ret,+is_called;
++++//+return+new+function+which+is+our+control+function+
++++//+to+make+sure+once_fn+is+only+called+once:
++++return+function(arg1,+arg2,+arg3)+{
++++++++if+(+is_called+)+return+ret;
++++++++is_called+=+true;
++++++++//+return+the+result+from+once_fn+and+store+to+so+we+can+return+it+multiply+times:
++++++++//+you+might+wanna+look+at+Function.prototype.apply:
++++++++ret+=+once_fn(arg1,+arg2,+arg3);
++++++++return+ret;
++++};
}|code-block|syntax|javascript|248483|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Initial setup:

<pre><code>var once = function( once_fn ) {
 var ret, is_called;
 // return new function which is our control function 
 // to make sure once_fn is only called once:
 return function(arg1, arg2, arg3) {
 if ( is_called ) return ret;
 is_called = true;
 // return the result from once_fn and store to so we can return it multiply times:
 // you might wanna look at Function.prototype.apply:
 ret = once_fn(arg1, arg2, arg3);
 return ret;
 };
}
</code></pre>

blocks|key|248534|text|如果您正在使用Node.js或编写带有browserify的JavaScript，请考虑"once"+npm+module|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|248535|var+once+=+require('once')

function+load+(file,+cb)+{
++cb+=+once(cb)
++loader.load('file')
++loader.once('load',+cb)
++loader.once('error',+cb)
}|code-block|syntax|javascript|248536|entityMap|0|LINK|mutability|MUTABLE|url|https://www.npmjs.org/package/once^0|18|H|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

If your using Node.js or writing JavaScript with browserify, consider the <a href="https://www.npmjs.org/package/once" rel="nofollow">"once" npm module</a>:

<pre><code>var once = require('once')

function load (file, cb) {
 cb = once(cb)
 loader.load('file')
 loader.once('load', cb)
 loader.once('error', cb)
}
</code></pre>

blocks|key|248700|text|如果您希望将来能够重用该函数，那么基于ed+Hopp上面的代码可以很好地工作(我意识到最初的问题并没有要求这个额外的功能！)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|248701|+++var+something+=+(function()+{
+++var+executed+=+false;++++++++++++++
++++return+function(value)+{
++++++++//+if+an+argument+is+not+present+then
++++++++if(arguments.length+==+0)+{+++++++++++++++
++++++++++++if+(!executed)+{
++++++++++++executed+=+true;
++++++++++++//Do+stuff+here+only+once+unless+reset
++++++++++++console.log("Hello+World!");
++++++++++++}
++++++++++++else+return;

++++++++}+else+{
++++++++++++//+otherwise+allow+the+function+to+fire+again
++++++++++++executed+=+value;
++++++++++++return;
++++++++}+++++++
++++}
})();

something();//Hello+World!
something();
something();
console.log("Reset");+//Reset
something(false);
something();//Hello+World!
something();
something();|code-block|syntax|javascript|248702|输出如下所示：|248703|Hello+World!
Reset
Hello+World!|248704|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|$]]

If you want to be able to reuse the function in the future then this works well based on ed Hopp's code above (I realize that the original question didn't call for this extra feature!):

<pre><code> var something = (function() {
 var executed = false; 
 return function(value) {
 // if an argument is not present then
 if(arguments.length == 0) { 
 if (!executed) {
 executed = true;
 //Do stuff here only once unless reset
 console.log("Hello World!");
 }
 else return;

 } else {
 // otherwise allow the function to fire again
 executed = value;
 return;
 } 
 }
})();

something();//Hello World!
something();
something();
console.log("Reset"); //Reset
something(false);
something();//Hello World!
something();
something();
</code></pre>

The output look like:

<pre><code>Hello World!
Reset
Hello World!
</code></pre>

blocks|key|465345|text|一个简单的例子就是只开一次灯。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|465346|function+turnOnLightOnce()+{
++let+lightOn+=+false;

++return+function+()+{
++++if+(!lightOn)+{
++++++console.log("Light+is+not+on...Turning+it+on+for+first+and+last+time");
++++++lightOn+=+true;
++++}

++};
}

const+lightOn+=+turnOnLightOnce();
lightOn()++//+Light+is+not+on...Turning+it+on+for+first+and+last+time
lightOn()
lightOn()
lightOn()
lightOn()|code-block|syntax|javascript|465347|https://codesandbox.io/s/javascript-forked-ojo0i?file=/index.js|offset|length|465348|这是由于JavaScript中的闭包造成的。|465349|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|1R|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|U|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|V|8|@]|9|@$I|W|J|X|1|Y]]|A|$]]|$1|K|3|L|5|6|7|Z|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|10|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|H]]]]

A simple example for turning on light only once.
<pre><code>function turnOnLightOnce() {
 let lightOn = false;

 return function () {
 if (!lightOn) {
 console.log(&quot;Light is not on...Turning it on for first and last time&quot;);
 lightOn = true;
 }

 };
}

const lightOn = turnOnLightOnce();
lightOn() // Light is not on...Turning it on for first and last time
lightOn()
lightOn()
lightOn()
lightOn()
</code></pre>
<a href="https://codesandbox.io/s/javascript-forked-ojo0i?file=/index.js" rel="nofollow noreferrer">https://codesandbox.io/s/javascript-forked-ojo0i?file=/index.js</a>
This happens due to closure in JavaScript.

blocks|key|248387|text|尝试使用下划线"once“函数：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|248388|var+initialize+=+_.once(createApplication);
initialize();
initialize();
//+Application+is+only+created+once.|code-block|syntax|javascript|248389|http://underscorejs.org/#once|offset|length|248390|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|T|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|S|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|T|8|@]|9|@$I|U|J|V|1|W]]|A|$]]|$1|K|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|H]]]]

Trying to use underscore "once" function:

<pre><code>var initialize = _.once(createApplication);
initialize();
initialize();
// Application is only created once.
</code></pre>

<a href="http://underscorejs.org/#once" rel="nofollow">http://underscorejs.org/#once</a>

blocks|key|465130|text|var+init+=+function()+{
++++console.log("logges+only+once");
++++init+=+false;
};+

if(init)+{+init();+}

/*+next+time+executing+init()+will+cause+error+because+now+init+is+
+++-equal+to+false,+thus+typing+init+will+return+false;+*/|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|465131|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>var init = function() {
 console.log("logges only once");
 init = false;
}; 

if(init) { init(); }

/* next time executing init() will cause error because now init is 
 -equal to false, thus typing init will return false; */
</code></pre>

blocks|key|465142|text|if+(!window.doesThisOnce){
++function+myFunction()+{
++++//+do+something
++++window.doesThisOnce+=+true;
++};
};|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|465143|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>if (!window.doesThisOnce){
 function myFunction() {
 // do something
 window.doesThisOnce = true;
 };
};
</code></pre>

blocks|key|248747|text|让它尽可能简单|type|unstyled|depth|inlineStyleRanges|entityRanges|data|248748|function+sree(){
++console.log('hey');
++window.sree+=+_=>{};
}|code-block|syntax|javascript|248749|你可以看到结果|248750|​|248751|📷|atomic|offset|length|248752|248753|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/f79ea11477860f35196ba6c935293c59.png|imageAlt^0|0|0|0|0|0|1|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|10|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|11|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|12|8|@]|9|@]|A|$]]|$1|K|3|L|5|M|7|13|8|@]|9|@$N|14|O|15|1|16]]|A|$]]|$1|P|3|J|5|6|7|17|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X|Y|-4]]]]

keep it as simple as possible

<pre><code>function sree(){
 console.log('hey');
 window.sree = _=&gt;{};
}
</code></pre>

You can see the result

<img src="https://i.stack.imgur.com/0Am2T.png" alt="script result">

blocks|key|248769|text|为了好玩把帽子扔进拳击场，增加了回忆的好处|type|unstyled|depth|inlineStyleRanges|entityRanges|data|248770|const+callOnce+=+(fn,+i=0,+memo)+=>+()+=>+i%2B%2B+?+memo+:+(memo+=+fn());|code-block|syntax|javascript|248771|//+usage
const+myExpensiveFunction+=+()+=>+{+return+console.log('joe'),5;+}
const+memoed+=+callOnce(myExpensiveFunction);
memoed();+//logs+"joe",+returns+5
memoed();+//+returns+5
memoed();+//+returns+5
...|248772|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|D|7|M|8|@]|9|@]|A|$E|F]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Tossing my hat in the ring for fun, added advantage of memoizing
<pre class="lang-js prettyprint-override"><code>const callOnce = (fn, i=0, memo) =&gt; () =&gt; i++ ? memo : (memo = fn());
</code></pre>
<pre class="lang-js prettyprint-override"><code>// usage
const myExpensiveFunction = () =&gt; { return console.log('joe'),5; }
const memoed = callOnce(myExpensiveFunction);
memoed(); //logs &quot;joe&quot;, returns 5
memoed(); // returns 5
memoed(); // returns 5
...
</code></pre>

blocks|key|465199|text|这对于防止无限循环很有用(使用jQuery)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|465200|<script>
var+doIt+=+true;
if(doIt){
++//+do+stuff
++$('body').html(String($('body').html()).replace("var+doIt+=+true;",+
++++++++++++++++++++++++++++++++++++++++++++++++++"var+doIt+=+false;"));
}+
</script>|code-block|syntax|javascript|465201|如果您担心名称空间污染，可以将一个长的随机字符串替换为"doIt“。|465202|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

This one is useful for preventing infinite loops (using jQuery):

<pre><code>&lt;script&gt;
var doIt = true;
if(doIt){
 // do stuff
 $('body').html(String($('body').html()).replace("var doIt = true;", 
 "var doIt = false;"));
} 
&lt;/script&gt;
</code></pre>

If you're worried about namespace pollution, subsitute a long, random string for "doIt".

blocks|key|465216|text|它有助于防止粘性执行|type|unstyled|depth|inlineStyleRanges|entityRanges|data|465217|var+done+=+false;

function+doItOnce(func){
++if(!done){
++++done+=+true;
++++func()
++}
++setTimeout(function(){
++++done+=+false;
++},1000)
}|code-block|syntax|javascript|465218|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

It helps to prevent sticky execution 

<pre><code>var done = false;

function doItOnce(func){
 if(!done){
 done = true;
 func()
 }
 setTimeout(function(){
 done = false;
 },1000)
}
</code></pre>

I need to create a function which can be executed only once, in each time after the first it won't be executed. I know from C++ and Java about static variables that can do the work but I would like to know if there is a more elegant way to do this?

Function in JavaScript that can be called only once

我需要创建一个只能执行一次的函数，每次执行第一次之后，它都不会被执行。我从C++和Java那里了解到静态变量可以完成这项工作，但我想知道是否有更优雅的方法来做到这一点？

问JavaScript中只能调用一次的函数
EN

回答 19

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问JavaScript中只能调用一次的函数EN

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问JavaScript中只能调用一次的函数
EN