jquery custom right-click menu, select all, discontinuous selection_jquery

Recently, I have to implement some custom effects in the project, such as right-click menu, select all, discontinuous selection, etc. I think the main thing is to clarify the logic and event relationships. To achieve this, there are also ready-made plug-ins available, such as jQuery UI's selectable.

1. Right-click menu
When browsing the web, right-click the mouse (or ctrl+left-click on the touchpad) and the browser's default right-click menu item will appear, like this:

But when you want to customize the right click on an element, like this:

You must first disable the browser's default menu and listen to the contextmenu event. The key code is as follows:

$(function(){
 $('#box').on('contextmenu',function(event){
 event.preventDefault();
  $(this).trigger('click');
  $('#menulist').css({
   top: event.pageY,
   left: event.pageX
  });
 });
 $('#box').click(function(){
  $('#menulist').css('display','block');
 });
})

2. Select all
The default ctrl+A (command+A under MAC) will select the entire web page or a focused editable element.

<div id='box'>
 <p class='first'>这是个div，这是个div，</p>
 <p>这是个div，这是个div，</p>
 <p>这是个div，这是个div，</p>
 <p>这是个div，这是个div，</p>
 <p>这是个div，这是个div，</p>
</div>
<div id='other'>
 <p class='first'>这是另外一个div，这是另外一个div，</p>
 <p>这是另外一个div，这是另外一个div，</p>
 <p>这是另外一个div，这是另外一个div，</p>
 <p>这是另外一个div，这是另外一个div，</p>
</div>

If there are only these two divs on the page, press ctrl/cmd+A and both divs will be selected. If you only want to select the content of div#box, the simple way is to add contentEditable=true to the div. Another way is to listen for keyboard events.

Simulate selecting all sub-elements p of div#box and highlighting them:

$(function(){
 $(document).keydown(function(event){
 //windows下是event.ctrlKey
 if(event.metaKey && event.which === 65){
  event.preventDefault();
  $('#box>p').trigger('click');
 }
 });
 $('#box').on('click', 'p', function(){
 $(this).css('color','red');
 });
});

3. Shift enables continuous selection
Shift is combined with the right mouse button to achieve continuous selection of elements, which is simply simulated here.

<div id='box' class="unselect">
 <p class='first'>这是个div，这是个div，</p>
 <p>这是个div，这是个div，</p>
 <p>这是个div，这是个div，</p>
 <p>这是个div，这是个div，</p>
 <p>这是个div，这是个div，</p>
</div>

When holding shift, the browser has a default continuous selection, disable it first:

.unselect{
 -webkit-user-select: none;
 -moz-user-select: none;
 -ms-user-select: none;
 -o-user-select: none;
 user-select: none;
}

For lower versions of IE, use the selectstart event:

$('#box')[0].onselectstart = function(e){
  e.preventDefault();
  return false;
 };

Register the click event for p, and listen to the keydown and keyup events of the document object:

$(document).keydown(function(e){
  if(e.shiftKey){
   shiftkey = 1;
  }
 }).keyup(function(){
  shiftkey = 0;
 });
$('#box').on('click','p',function(){
  if(shiftkey === 1){
   second = $(this).index();
   for(var min = Math.min(first,second); min <= Math.max(first,second); min++){
    $('#box').find('p').eq(min).css('color','red');
   }
  } else {
   first = $(this).index();
   $(this).css('color','red').siblings().css('color','black');
  }
 })

4. Discontinuous selection
Discontinuous selection requires monitoring the ctrl key (command key under mac) and registering a click event for the element.

 $(document).keydown(function(e){
  if(e.metaKey){ //win是e.ctrlKey
   ctrlkey = 2;
  }
 }).keyup(function(){
  ctrlkey = 0;
 });
 $('#box').on('click','p',function(){
  if(ctrlkey === 2){
   $(this).css('color','red');
  } else {
   $(this).css('color','red').siblings().css('color','black');
  }
 })

The above is the entire content of this article. I hope it will be helpful to everyone in learning jquery programming.