为什么 jQuery 会破坏这段代码？

Question

When i use a jQuery id selector to select an element, it does not function the same as if i use plain JS. Why does the does the display block, or the src not change when using jQuery, but works with plain JS?

See JS line 2 has working code comment that out and uncomment line 3 and select the element with the jQuery and it stops working.

HTML

<img id="myImg" src="https://i.ytimg.com/vi/tntOCGkgt98/maxresdefault.jpg" alt="Trolltunga, Norway" width="300" height="200">

<!-- The Modal -->
<div id="myModal" class="modal">
  <span class="close">×</span>
  <img class="modal-content" id="img01">
  <div id="caption"></div>
</div>

JS

// Get the modal
var modal = document.getElementById('myModal');
// var modal = $("#myModal");

// Get the image and insert it inside the modal - use its "alt" text as a caption
var img = document.getElementById('myImg');
var modalImg = document.getElementById("img01");
var captionText = document.getElementById("caption");
img.onclick = function(){
    modal.style.display = "block";
    modalImg.src = this.src;
    captionText.innerHTML = this.alt;
}

// Get the <span> element that closes the modal
var span = document.getElementsByClassName("close")[0];

// When the user clicks on <span> (x), close the modal
span.onclick = function() {
    modal.style.display = "none";
}

http://codepen.io/Zlerp/pen/xEqEAQ?editors=1010

Answer 1

Very simple. When jQuery selects an element, it isn't the ELEMENT per se it's selecting, it's a jQuery object containing that element. If you do $("selector")[0], that will return the correct object. Or you can set style using the css function, eg $("selector").css("property","value").