How to implement the starry navigation bar in JS

This time I will show you how to implement the star-filled navigation bar with JS. What are the precautions for implementing the star-filled navigation bar with JS? The following is a practical case, let’s take a look.

Instructions

Share the effect of a starry navigation bar. There is not much code, but the effect is very beautiful. Let’s take a look at the rendering first.

Explanation

To achieve this effect, you don’t need a lot of knowledge. You know simple CSS and can use JS to get elements. It is basically enough to be able to bind events.

Okay, let’s look at the code directly. The comments have been written in great detail. If you don’t want to see the comments, click here to preview.

nbsp;html>

 
 <meta>
 <style>
body {
 background-color: #000;
 /* 防止出现左右的滚动条 */
 overflow: hidden;
 margin: 0;
 padding: 0;
}
.wrapper {
 width: 100%;
 height: 100px;
}
.wrapper .nav {
 list-style: none;
 width: 800px;
 height: 100px;
 padding: 0;
 margin: 0 auto;
}
.wrapper .nav li {
 width: 25%;
 height: 50px;
 float: left;
 margin-top: 25px;
}
.wrapper .nav li a {
 text-decoration: none;
 color: #fff;
 text-align: center;
 line-height: 50px;
 display: block;
 font-size: 20px;
 font-family: "KaiTi";
}
/* 闪烁的星星 的基本样式 */
.star {
 width: 5px;
 height: 5px;
 background: #fff;
 position: absolute;
 z-index: -1;
}
/* 闪烁动画，改变透明度 */
@keyframes blink {
 from {
 opacity: 0.2;
 }
 to {
 opacity: 1;
 }
}
</style>
 
 
 <p>
  </p>

  
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  <script> // 定义一个 starrySky 对象 var starrySky = { // 星星的数量 starNum: 100, // 星星的大小，返回一个 2 ~ 12 的随机数 starSize () { return 2 + Math.trunc(Math.random() * 10) }, // 星星的颜色 starColor: "#fff", // 线的颜色，鼠标进入导航区域，星星会连成一条线 lineColor: "#fff", // 线的高度 lineHeight: "3px", // 星星连成线的时间 changeTime: "1s", // 初始化方法，生成需要的星星，并调用需要的方法 init () { var html = ""; // 循环生成星星 for (var i = 0; i < this.starNum; i++) { html += "<p class=&#39;star&#39; id=&#39;star" + i + "&#39;>"; } // 拼接到 元素wrapper 中 document.querySelector(".wrapper").innerHTML += html; // 调用 星星分散 的方法 this.disperse(); // 调用 星星聚合连成线 的方法 this.combine(); }, disperse () { // 这个that 保存的是 starrySky 对象 var that = this; // 获取 元素wrapper 的宽度 var width = document.querySelector(&#39;.wrapper&#39;).offsetWidth; // 获取 元素wrapper 的高度 var height = document.querySelector(&#39;.wrapper&#39;).offsetHeight; // 循环，开始在元素wrapper 区域内，生成规定数量的 星星， for (var i = 0; i < that.starNum; i++) { // 星星的 top值，0 ~ 元素wrapper 高度的随机数 var top = Math.trunc(height * Math.random()); // 星星的 left值，0 ~ 元素wrapper 宽度的随机数 var left = Math.trunc(width * Math.random()); // 星星的大小，调用 starrySky对象的starSize()方法 var size = that.starSize(); // 设置分散时每个星星样式 document.querySelector("#star" + i).style.cssText += ` top:${top}px; left:${left}px; width:${size}px; height:${size}px; background:${that.starColor}; opacity:${Math.random()}; border-radius:50%; animation:blink 1s ${Math.random() * 2}s infinite alternate; `; } }, combine () { // 这个that 保存的是 starrySky 对象 var that = this; // 查找导航栏 里所有的 a元素，遍历他们，每个都绑定上 鼠标进入 和 鼠标移出 事件 document.querySelectorAll(".nav li a").forEach(function (item) { item.addEventListener("mouseover", function (e) { // 这里的this 是触发事件的当前节点对象，就是鼠标进入时候的 a元素 // 当前a元素的宽度 / 星星数 = 最后连成线时，星星的宽度 var width = this.offsetWidth / that.starNum; // 遍历，为每个星星修改样式，开始连成线 for (var i = 0; i < that.starNum; i++) { // 星星的top 值就是，当前a元素的距离顶部的值 + 当前a元素的高度 var top = this.offsetTop + this.offsetHeight; // 星星的left 值就是，当前a元素的距离左边界的值 + 第i个星星 * 星星的宽度 var left = this.offsetLeft + i * width // 设置每个星星连成线时的样式 document.querySelector("#star" + i).style.cssText += ` width:${width}px; top:${top}px; left:${left}px; height:${that.lineHeight}; background:${that.lineColor}; opacity:1; border-radius:0; transition:${that.changeTime}; animation:blink 1s infinite alternate; `; } }); // 鼠标移出 调用 星星分散 的方法 item.addEventListener("mouseout", function () { that.disperse(); }); } ); }, } // 调用 starrySky对象的 init方法，实现满天星效果 starrySky.init(); </script>   Note: If you need to modify the style, do not position the nav element and the li element inside the nav, because the position of the last line is positioned based on the offsetHeight and offsetLeft of the a element. If the nav element and nav If the li element inside is positioned, the offsetParent element of the a element will be changed, and the position will be wrong.

If you don’t understand offsetHeight, offsetLeft and offsetParent, click here: https://codepen.io/FEWY/pen/MQdoWX

Summary

To achieve this effect, we need to make a starrySky object and define some necessary attributes, mainly relying on the two methods disperse() and combine(). When the stars need to be dispersed, call disperse(), and when the stars need to be connected in a line, call combine (), okay that’s it.

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:

How to update the array with $set in vue.js

How to move the array in vue.js Position and update the view

The above is the detailed content of How to implement the starry navigation bar in JS. For more information, please follow other related articles on the PHP Chinese website!