blocks|key|562440|text|在函数的末尾添加以下行：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|562441|function+getH4()+{
++++//+...

++++window.onscroll+=+null;
}|code-block|syntax|javascript|562442|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|$]]

Add the following line at the end of your function:

<pre><code>function getH4() {
 // ...

 window.onscroll = null;
}
</code></pre>

blocks|key|2473697|text|创建一个全局布尔变量并将其设置为false。再次在窗口滚动事件中将其设置为true，并使用if块检查变量为false。将您的代码放在if块中。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2473698|var+isScrolled+=+false;

function+getH4()+{
++++if(!isScrolled){
++++++++//your+code
++++}
++++isScrolled+=+true
}|code-block|syntax|javascript|2473699|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|$]]

create a global boolean variable and set it to false. again set it to true in the window scroll event and chk the variable is false using a if block. put your code inside that if block.

<pre><code>var isScrolled = false;

function getH4() {
 if(!isScrolled){
 //your code
 }
 isScrolled = true
}
</code></pre>

blocks|key|2473715|text|您只需在JavaScript函数末尾将onscroll属性设置为none，如下所示：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2473716|window.onscroll+=+null;|code-block|syntax|javascript|2473717|现在，当脚本第一次执行时，它将执行它的功能，上面的代码行会将onscroll设置为null，因此不会在鼠标滚动时调用任何事件，因此您的函数不会在事件中一次又一次地被调用，除非是第一次。|2473718|或者，您可以通过设置一个公共变量(比如var+check+=+0+)来逻辑地处理它，然后在第一次输入时将该变量设置为1。因此，您需要检查check的值，并根据该值执行函数|2473719|var+check+=+1;
function+getH4()+{
++++if(check==1)
++++{
++++var+xyz+=+document.getElementsByClassName('bucket_left');
++++for(var+i=0;i<xyz.length;i%2B%2B){
++++++++var+x=document.getElementsByTagName("h4")[i].innerHTML;
++++++++var+current_bucket+=+xyz[i];
++++++++var+y=current_bucket.firstChild.href;
++++++++var+newdiv+=+document.createElement('div');
++++++++newdiv.innerHTML+=+"<a+href=\""%2By%2B"\">"%2Bx%2B"</a>";
++++++++newdiv.className+=+"hover_title_h4";
++++++++current_bucket.appendChild(newdiv);
+++++}
++++++++check=0;
++++}
}|2473720|entityMap^0|J|8|0|0|U|8|0|J|D|1W|5|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|Z|8|@$9|10|A|11|B|C]|$9|12|A|13|B|C]]|D|@]|E|$]]|$1|O|3|P|5|H|7|14|8|@]|D|@]|E|$I|J]]|$1|Q|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|R|$]]

You only have to set the <code>onscroll</code> property to none as following at the end of you JavaScript function:

<pre><code>window.onscroll = null;
</code></pre>

Now when the script executes for the first time, it will perform its function and the above line will set the <code>onscroll</code> to null and thus will not invoke any event on scroll of your mouse and so your function wont be invoked again and again on the event except for the first time.

Or you could handle it logically by setting a public var say <code>var check = 0</code> and then set the variable to 1 when entered for the first time. So you need to check the value of <code>check</code> and based on that execute the function

<pre><code>var check = 1;
function getH4() {
 if(check==1)
 {
 var xyz = document.getElementsByClassName('bucket_left');
 for(var i=0;i&lt;xyz.length;i++){
 var x=document.getElementsByTagName("h4")[i].innerHTML;
 var current_bucket = xyz[i];
 var y=current_bucket.firstChild.href;
 var newdiv = document.createElement('div');
 newdiv.innerHTML = "&lt;a href=\""+y+"\"&gt;"+x+"&lt;/a&gt;";
 newdiv.className = "hover_title_h4";
 current_bucket.appendChild(newdiv);
 }
 check=0;
 }
}
</code></pre>

blocks|key|3703458|text|您可以尝试这样做:当滚动时，check等于false，append事件将只发生一次；当scroll+end(mouseup或mouseout)，check等于true时，您可以再次追加。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3703459|var+check+=+true;
function+getH4(event)+{
++++event.target.onmouseup+=+function()+{
++++++++check+=+true;
++++}
++++event.target.onmouseout+=+function()+{
++++++++check+=+true;
++++}
++++if+(check)+{
++++++++var+xyz+=+document.getElementsByClassName('bucket_left');
++++++++for(var+i=0;i<xyz.length;i%2B%2B){
++++++++++++var+x=document.getElementsByTagName("h4")[i].innerHTML;
++++++++++++var+current_bucket+=+xyz[i];
++++++++++++var+y=current_bucket.firstChild.href;
++++++++++++var+newdiv+=+document.createElement('div');
++++++++++++newdiv.innerHTML+=+"<a+href=\""%2By%2B"\">"%2Bx%2B"</a>";
++++++++++++newdiv.className+=+"hover_title_h4";
++++++++++++current_bucket.appendChild(newdiv);
++++++++}
++++check+=+false;
}

window.onscroll=getH4|code-block|syntax|javascript|3703460|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|$]]

you can try this:
when scrolling,the check equal false, and the append event will happen just once;
when the scroll end(mouseup or mouseout), the check equal true, you can append again.

<pre><code>var check = true;
function getH4(event) {
 event.target.onmouseup = function() {
 check = true;
 }
 event.target.onmouseout = function() {
 check = true;
 }
 if (check) {
 var xyz = document.getElementsByClassName('bucket_left');
 for(var i=0;i&lt;xyz.length;i++){
 var x=document.getElementsByTagName("h4")[i].innerHTML;
 var current_bucket = xyz[i];
 var y=current_bucket.firstChild.href;
 var newdiv = document.createElement('div');
 newdiv.innerHTML = "&lt;a href=\""+y+"\"&gt;"+x+"&lt;/a&gt;";
 newdiv.className = "hover_title_h4";
 current_bucket.appendChild(newdiv);
 }
 check = false;
}

window.onscroll=getH4
</code></pre>

<pre><code>function getH4() {
 var xyz = document.getElementsByClassName('bucket_left');
 for(var i=0;i&lt;xyz.length;i++){
 var x=document.getElementsByTagName("h4")[i].innerHTML;
 var current_bucket = xyz[i];
 var y=current_bucket.firstChild.href;
 var newdiv = document.createElement('div');
 newdiv.innerHTML = "&lt;a href=\""+y+"\"&gt;"+x+"&lt;/a&gt;";
 newdiv.className = "hover_title_h4";
 current_bucket.appendChild(newdiv);
 }
}

window.onscroll=getH4;
</code></pre>

In above code i want to append new <code>div</code> in set of <code>div</code>s having class <code>bucket_left</code> and this <code>div</code>s generated from infinite scrolling. above code is working fine but on scroll it appends so many <code>div</code>s. 
so how do i append only once ?

How to call javascript function only once during window.onscroll event?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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function getH4() { var xyz = document.getElementsByClassName('bucket_left'); for(var i=0;i<xyz.length;i++){ var x=document.getElementsByTagName("h4...

问如何在window.onscroll事件中只调用一次javascript函数？
EN

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问如何在window.onscroll事件中只调用一次javascript函数？EN