Question

如何在第一次使用javascript滚动页面时提醒？

我只想提醒第一个滚动页面，我该怎么做？

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script type="text/javascript">
  $(window).scroll(function () {
var xxx;
if(xxx === '')
{
    var xxx = "test";
    var div = $("#myDiv");
    alert(div.height());
}
  });
</script>
<DIV id="myDiv" style="height:auto; width:78;overflow:hidden"> Simple Test</DIV>
<br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
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Answer 1

使用.one()

将处理程序附加到元素的事件。处理程序已执行每个事件类型每个元素最多一次。

$(window).one("scroll", function() {
    console.log("foo");
});

fiddle

Answer 2

将变量作为全局变量并使用布尔值而不是字符串，这在使用代码标志时更好。除此之外，在滚动函数中设置变量时无需重新定义变量。

＆＃13;

var xxx; 

$(window).scroll(function () {

if(!xxx)
{
    xxx = true;
    var div = $("#myDiv");
    alert(div.height());
}
  });

＆＃13;

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>

<DIV id="myDiv" style="height:auto; width:78;overflow:hidden"> Simple Test</DIV>
<br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
<br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>

＆＃13;

Answer 3

   onscroll = function () {
          var xxx = "test";
          var div = $("#myDiv");
          alert(div.height());
      
        onscroll = null; // remove function so wont get called next time
   };

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<DIV id="myDiv" style="height:auto; width:78;overflow:hidden"> Simple Test</DIV>
<br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
<br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>

Answer 4

此代码仅在用户在页面上进行第一次滚动时发出警报。

var scrolled = false;
$(window).scroll(function() { if (scrolled == false) { alert("You Have Just Scrolled"); scrolled = true; } });

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>
<div>This is some text</div>

如何在第一次使用javascript滚动页面时提醒？

4 个答案: