How to implement the hide and show function of elements in css

In web development, we often need to use css to control the hiding and display of elements. This can help us optimize page layout, improve user experience, and achieve different interactive effects. This article will introduce how to use CSS to hide and show elements, as well as some practical application scenarios.

css controls the display and hiding of elements

In css, there are several properties that can help us control the display and hiding of elements, including display, visibility and opacity.

display attribute

display attribute is the most commonly used method to control the hiding and display of elements. This attribute can specify whether the element is shown or hidden on the page, and can control the layout of the element. There are many values ​​for the display attribute. Here are some commonly used values ​​and their meanings:

• none: Completely hide the element and do not occupy page space
• block: The element is displayed in a block and occupies the entire width of the parent container. Each block is wrapped with the preceding and following elements.
• inline: The element is displayed inline, and Will be affected by other inline elements, but will not destroy the flow of text
• inline-block: The element is displayed in an inline block, similar to inline, but can specify its own width, height and Margin

In addition to the values ​​listed above, the display attribute can also accept other values, including flex, grid, and table etc. These values ​​allow for a more flexible layout.

visibility attribute

visibilityThe attribute is used to control the visibility of the element, but the element will still occupy page space after it is hidden. There are only two values ​​for this attribute:

• visible: The element is visible
• hidden: The element is hidden, but still takes up page space

Compared with the display attribute, the visibility attribute has less impact and is usually used to achieve animation effects of some text and images.

opacity attribute

opacity attribute is used to control the transparency of the element. Its value is a number between 0 and 1. 0 means completely transparent and 1 means completely opaque. . By changing the transparency of elements, we can achieve some fade-in and fade-out effects.

How to hide and show elements in css

In addition to the properties introduced above, we can also hide and show elements by setting class names. Specifically, we can set a class name for the element, and then control the display and hiding of the element by adding or removing this class name.

The following is an example to display or hide a div element by clicking a button:

<button id="b">点击我</button>
<div id="hideDiv" class="hide">这是一个隐藏的div</div>

.hide {
  display: none;
}

var button = document.getElementById('b');
var hideDiv = document.getElementById('hideDiv');

button.onclick = function() {
  if (hideDiv.classList.contains('hide')) {
    hideDiv.classList.remove('hide');
  } else {
    hideDiv.classList.add('hide');
  }
}

In the above code, we set the display attribute of the hidden div element to none through css, and then Added a class name to it. In the javascript code, we listen to the click event of the button, and determine whether to remove or add its hidden class name by judging the class name of the div element each time it is clicked.

Actual application scenarios

Hide and display of control elements are very common in actual web development. Here are a few examples:

Navigation menu

When When the user clicks on the navigation menu or drop-down menu, we can expand and contract the menu by controlling the display and hiding of menu items.

Modal boxes

Modal boxes are often used when users interact with websites. We can create a modal div element and control the display and hiding of the modal by adding and removing class names.

Title Card

Sometimes, we need to display some content cards on the page, each card has a title and content. If we displayed all the cards on the page, the page would become very crowded. Therefore, we can achieve a concise page layout by controlling the display and hiding of card elements.

In general, controlling the hiding and display of elements is a very common operation in web development. By using CSS attributes and class names, we can easily implement this function and provide users with a better interactive experience.

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