如何通过jQuery设置CSS的z-index属性？正确添加z-index:200的方法

Hey there! Let's walk through exactly how to set the CSS z-index property using jQuery, including the specific case of setting it to 200. It's pretty simple once you know the right tools.

The most common way to adjust z-index with jQuery is using the .css() method. Here's how you do it for different scenarios:

• Target a single element by ID:
  If your element has an ID like #modal, just run:

  $('#modal').css('z-index', 200);
  

  You can also pass the value as a string ('200') instead of a number—both work perfectly fine.

• Target multiple elements by class:
  For all elements with a class like .popup, use:

  $('.popup').css('z-index', 200);
  

If your element doesn't have a positioned value (required for z-index to work—more on that below), you can set both position and z-index in one go:

$('#myElement').css({
  'position': 'relative',
  'z-index': 200
});

Sometimes you might need to grab the current z-index first before updating it. For example, to increment the value:

// Get the current z-index (returns a string, so we convert it to a number)
let currentZ = parseInt($('#myElement').css('z-index'));
// Set it directly to 200
$('#myElement').css('z-index', 200);
// Or, if you want to build on the current value:
// $('#myElement').css('z-index', currentZ + 100);

• z-index only works on positioned elements: Your element must have position: relative, absolute, fixed, or sticky set. If it doesn't, the z-index value will be ignored—this is one of the most common mistakes!
• Stacking context matters: If the parent element of your target has a lower z-index, your element won't appear above elements outside the parent's stacking context. Double-check parent styles if your z-index isn't behaving as expected.

内容的提问来源于stack exchange，提问作者user3903810