更改图像点击和鼠标悬停

Question

I am a complete nub with JS, but I fiddle with it occasionally when necessary. I am writing a function that changes two images on a page (before & after gallery images) when a sliding image is click / selected from a marquee below them. I have that working. The problem is that I also need to change the AFTER image when the BEFORE image is moused over, and I dont seem to be able to pass that variable to the function correctly - here is what I have:

<script>
  function changeImage(imgName)
  {
 var img = imgName;
 img += 'a.jpg';
 var img1 = imgName;
 img1 += 'b.jpg';

 image = document.getElementById('imgDisp');
 image.src = img;    

 image = document.getElementById('imgDisp1');
 image.src = img1; 
  }


  function swap1(image)
  {
 var img = 'newgallery/';
 img += image;
 img += 'b.jpg';
     image = document.getElementById('imgDisp');
     image.src = img;    

  }


  function swap2(image)
  {
 var img = 'newgallery/';
 img += image;
 img += 'a.jpg';
     image = document.getElementById('imgDisp');
     image.src = img;    
  }
</script>



<table border=0 width=85%>
<tr>
<td align=center valign=top>
<img  id="imgDisp1" src=newgallery/1b.jpg height=80 
onmouseover="swap1(img)" 
onmouseout="swap2(img)"
>
<p class=content>BEFORE</b></p></td>
<td width=35></td>
<td align=center><img id="imgDisp" src=newgallery/1a.jpg width=550></td>
</tr>
</table>


<marquee behavior="scroll" direction="left" scrollamount="3"     onMouseOver="this.stop();" onMouseOut="this.start();">


<?php

$imagenum = '1';
$imageset = 'a.jpg';
$imagesetalt = 'b.jpg';

while($imagenum < 37){

$imagename = "$imagenum$imageset";
$imagethumb = "$imagenum$imagesetalt";

if($imagenum == '13'){

}else{

echo"               
<img src=\"newgallery/$imagename\" height=\"120\" border=0    onclick=\"changeImage('newgallery/$imagenum')\">
<img src=images/spacer.gif width=25 height=1>";

}

$imagenum++;

}


?>

I can change the images on click in the marquee calling the changeImage function because I can pass the assigned image name variable to the function. I cannot seem to figure out how to pass the BEFORE thumbnail image name variable to the mouseover functions (swap1) & (swap2) respectively. This may just be a simple syntax solution - but again I dont know JS well enough to figure it out - any assistance would be appreciated.

Answer 1

Honestly, your code is a little overcomplicated. You can simplify this by taking advantage of the data attribute of HTML elements.

Lets say you have a container defined as

<div id = 'img_container' class = 'some_class'>
  <img id = 'image' class = 'some_image_class' src = '/path/to/default/image.jpg'  
     data-alt = '/path/to/hover/image.jpg' />
</div>

You can define a function to retrieve the path stored in the data attribute and swap the data and source values via

function swap(image){
  //temporary variable to hold the alternate image path
  var newImage = image.data("alt");

  //store the image src attribute in the `data-alt` attribute
  image.data("alt", image.attr("src");

  //replace the image src attribute with the new image path
  image.attr("src", newImage);

}

Now, you can apply events to the image via

$("#image").on("mouseover", function(e){
                 swap($(e.currentTarget));
              })
              .on("mouseout", function(e){
                 swap($(e.currentTarget));
              });

This will allow you to replace the onmouseover and onmouseout events in your HTML.