Highlight all elements with same class when one of them is moused over

Question

In JavaScript, is it possible to highlight all items with the same class when one of them is moused over?

For example, if I had two paragraphs with the class p1

Answer 1

Here's a working example (which requires JQuery). When a member of p1 is moused over, all other elements of p1 will be highlighted as well. The same is true of p2.

JavaScript:

function highlightAllOnMouseover(className){
    $(className).mouseover(function() {
  $(className).css("opacity", 0.4); 
  $(className).css("opacity", 1);
}).mouseleave(function() { 
    $(className).css("opacity", 0.4);
});
}
highlightAllOnMouseover(".thing1");
highlightAllOnMouseover(".thing2");

HTML:

This is thing1.
This is thing2.
This is also thing1.
This is also thing2.

To cause all elements with a specific class to be highlighted on mouseover, you only need to call the function highlightAllOnMouseover(className), which I created here.