Detailed explanation of the use of Emergence.js plug-in

This time I will bring you a detailed explanation of the use of the Emergence.js plug-in. What are the precautions when using the Emergence.js plug-in? The following is a practical case, let's take a look.

Emergence.js is a lightweight, high-performance JS plugin for detecting and manipulating elements in the browser.

This plugin is designed to allow manipulation of elements based on their visibility in the browser. It gives developers the freedom to use their own CSS or JS to view animations or state changes. It leverages HTML5 data attributes instead of classes to simplify development. Emergence.js is one of the lightest and most compatible plugins of its kind.

Features of emergence.js

No need to rely on other components

1. Supports IE8 and all modern browsers

2. Only 1kb after compression

Install

Installation of Emergence.js is very simple. The installation method of npm is as follows:

npm install emergence.js

In addition, we can also download it directly and introduce Emergence.js in the html file.

<script src="path/to/emergence.min.js"></script>
<script>
 emergence.init();
</script>

how to use

Add data-emergence="hidden" to any element you want to watch:

< p class = “ element ” data-emergence = “ hidden ” > </ p >

When the element becomes visible within the viewport, the attribute changes to data-emergence="visible" . Now you can leverage CSS to animate elements:

.element [ data-emergence = hidden ] {
 / *隐藏状态* /
}
.element [ data-emergence = visible ] {
 / *可见状态* / 
}

Custom options

Emergence.js has many options to customize. The following are the default values:

emergence.init({
 container: window,
 reset: true,
 handheld: true,
 throttle: 250,
 elemCushion: 0.15,
 offsetTop: 0,
 offsetRight: 0,
 offsetBottom: 0,
 offsetLeft: 0,
 callback: function(element, state) {
 if (state === 'visible') {
  console.log('Element is visible.');
 } else if (state === 'reset') {
  console.log('Element is hidden with reset.');
 } else if (state === 'noreset') {
  console.log('Element is hidden with NO reset.');
 }
 }
});

Option Description

container: Container, by default the visibility of the element will be determined by the window's viewport dimensions and X/Y scroll position (set to window). However, it can be changed to a custom container. For example:

var customContainer = document.querySelector('.wrapper');
// www.xttblog.com
emergence.init({
 container: customContainer
});

Throttle: is a way to prevent performance issues related to scrolling and resizing

events

. Throttle will create a small timeout and steadily check the element's visibility every certain amount of milliseconds during the event. The default is 250. reset: Determines whether the data attribute state is reset after display. Reset it to false if you want the element to maintain its displayed state even after leaving the viewport. The default is true.

handheld: Emergence will perform checks for most handheld device models such as phones and tablets. When set to false, the plugin will not run on these devices. The default is true.

elemCushion: Element coordinates will determine how many elements need to be "visible" within the viewport. A value of 0.5 will equal 50% of the elements that need to be visible. The default is 0.15.

offsetTop, offsetRight, offsetBottom, offsetLeft: Provides an offset (in pixels) on any side of the viewport. This is useful if you have a fixed component (such as a header) that you can offset by the same value for the header's height. A value of 100 applied to offsetTop will mean that an element will only be considered visible if it is greater than 100 pixels from the top of the viewport. All default values ​​are 0.

callback: Used to provide callbacks to determine when an element is visible, hidden, and reset. Possible states are visible, reset and noreset.

In addition, Emergence.js also provides two advanced methods emergence.engage(); and emergence.disengage(); whose functions are exactly opposite.

Emergence.js relies on the following browser API: querySelectorAll

To support IE8, please ensure standards mode.

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!

Recommended reading:

What are the ways to implement Ajax asynchronously in native JS

Operation modal single load data

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