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前端：HTML+CSS+JavaScript實現(xiàn)輪播圖2
- 1. 和之前版本的區(qū)別
- 2. 實現(xiàn)原理
- 3. 針對上述的改進
- 3. 參考代碼
1. 和之前版本的區(qū)別
之前發(fā)布的那篇關于輪播圖的文章在這：前端：HTML+CSS+JavaScript實現(xiàn)輪播圖，只能說存在問題吧！比如2、3實現(xiàn)效果是用了兩個定時器實現(xiàn)的，雖然也達到了那種效果，但是從一些方面來說總有點繁瑣吧！比如，在一定時間內(nèi)圖片移動像素的計算等?，F(xiàn)在這個不需要計算，直接用一個定時器即可實現(xiàn)，我想說現(xiàn)在這個版本和各位在瀏覽器上看到那種效果實現(xiàn)原理應該差不多。
雖然沒有給出相應的點擊事件哈！
2. 實現(xiàn)原理
利用相對定位relative、絕對定位absolute、定時器、transition
結(jié)合relative、absolute來進行圖片布局，用定時器來實現(xiàn)圖片輪播間隔效果，用transition來實現(xiàn)每張圖片移動過渡效果。
初始實現(xiàn)效果如上，這不符合我們想要的那種效果，這種是通過定時器每隔幾秒變化每張圖片的left的值的效果。這并不怎么美觀，因為圖片過渡效果并不符合我們的要求，但是如果顯示的有多張圖片，那么倒還不錯，如下：
3. 針對上述的改進
就是把所有圖片從左到右進行排列，外層用一個標簽元素包裹，每隔一段時間變換外層的標簽元素的left屬性值。
3. 參考代碼
這個是需要改進的代碼哈！
main.html
<!DOCTYPE html>
<html>
<head><meta charset="utf-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><title></title><link rel="stylesheet" href="./main.css">
</head>
<body><div class="main"></div>
</body>
<script type="text/javascript" src="main.js"></script>
</html>
main.css
*{padding: 0;margin: 0;
}ul{list-style: none;
}.main{width: 500px;height: 300px;margin: 0 auto;position: relative;
}.dot{height: 10px;position: absolute;bottom: 20px;left: 50%;transform: translateX(-50%);
}.dot span{height: 100%;float: left;width: 10px;border-radius: 50%;margin-left: 10px;cursor: pointer;
}.dot span:first-child{margin-left: 0;
}.red{background-color: red;
}.white{background-color: white;
}.main ul{position: relative;height: 100%;width: 100%;overflow-x: hidden;
}.main ul li{position: absolute;top: 0;transition: all 0.3s;width: 100%;height: 100%;
}.main ul li img{width: 100%;
}
main.js
// 輸入圖片鏈接數(shù)組
const img_arr = ['https://i0.hdslb.com/bfs/banner/627984a9617a35c7e4366e0c74baf29ef3aa96ae.png@976w_550h_1c_!web-home-carousel-cover.avif','https://i0.hdslb.com/bfs/banner/3464f3b055107b2b54b9443e02c43448c0915866.png@976w_550h_1c_!web-home-carousel-cover.avif','https://i0.hdslb.com/bfs/banner/ff7d11c786ddd45c218696c3c6b19c69a71883d7.jpg@976w_550h_1c_!web-home-carousel-cover.avif','https://i0.hdslb.com/bfs/sycp/creative_img/202311/74214ce12c94ba104322e2be463ec6f7.jpg@976w_550h_1c_!web-home-carousel-cover.avif'
];const mainEle = document.querySelector('.main');
var _htmlStr = '';
img_arr.forEach(function(ele){_htmlStr += `<li><img src="${ele}"></li>`
})var _htmlStr2 = '';
for(let i=0;i<img_arr.length;i++){_htmlStr2 += '<span></span>'
}var _htmlStr2 = `<div class="dot">${_htmlStr2}</div>`;
_htmlStr = `<ul>${_htmlStr}</ul>${_htmlStr2}`;mainEle.innerHTML = _htmlStr;const img_width = 500;const elements = document.querySelectorAll('.main ul li');
const elements2 = document.querySelectorAll('.dot span');
elements.forEach(function(ele,index){ele.style.left = index * img_width + 'px';
})elements2.forEach(function(ele,index){if(index == 0){ele.className = 'red';}else{ele.className = 'white';}
})function left(){elements.forEach(function(ele,index){let left_v = parseFloat(ele.style.left);if(left_v - img_width < 0){ele.style.left = (elements.length - 1) * img_width + 'px';}else{ele.style.left = left_v - img_width + 'px';}if(left_v - img_width == 0){elements2[index].className = 'red';}else{elements2[index].className = 'white';}})
}var timer = setInterval(left,2000);這個是改進版本
main.html
<!DOCTYPE html>
<html>
<head><meta charset="utf-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><title></title><link rel="stylesheet" href="./main.css">
</head>
<body><div class="main"><div class="pre_ul" id="main"><ul><li><img src="https://i1.hdslb.com/bfs/archive/da52b26129a84aa316383d53e596d3f89c708294.jpg@672w_378h_1c_!web-home-common-cover.avif" alt=""></li><li><img src="https://i0.hdslb.com/bfs/archive/6df10d7e0834f8511ea620dbfe6bfc7b1eabdab2.jpg@672w_378h_1c_!web-home-common-cover.avif" alt=""></li><li><img src="https://i0.hdslb.com/bfs/archive/47338bc6056b6bbc906155590c6e201ae5dffee8.jpg@672w_378h_1c_!web-home-common-cover.avif" alt=""></li></ul></div><div class="dot" id="main"><span class="red"></span><span class="white"></span><span class="white"></span></div></div>
</body>
<script type="text/javascript" src="main.js"></script>
</html>
main.css
*{margin: 0;padding: 0;
}ul{list-style: none;
}.main{width: 500px;height: 300px;position: relative;margin: 0 auto;overflow-x: hidden;
}.main .dot{position: absolute;bottom: 8%;left: 50%;transform: translateX(-50%);height: 12px;z-index: 2;
}.dot span{float: left;height: 100%;width: 12px;border-radius: 50%;cursor: pointer;margin-left: 8px;
}.dot span:first-child{margin-left: 0;
}.white{background-color: white;
}.red{background-color: red;
}.main .pre_ul{height: 100%;position: absolute;top: 0;left: 0;transition: all 0.5s;z-index: 1;
}.main .pre_ul ul{width: 100%;height: 100%;position: relative;overflow-x: hidden;
}.main .pre_ul ul li{height: 100%;position: absolute;top: 0;left: 0;
}.main .pre_ul ul li img{width: 100%;
}main.js
const img_width = 500;
// 圖片最大寬度
const eles = document.querySelectorAll('.pre_ul ul li');
const pre_ul_ele = document.querySelector('.pre_ul');
const dots = document.querySelectorAll('.dot span');
const n = eles.length;
pre_ul_ele.style.left = 0;
pre_ul_ele.style.width = n * img_width + 'px';
eles.forEach(function(ele,index){ele.style.width = img_width + 'px';ele.style.left = index * img_width + 'px';
})function clear_red(){dots.forEach(function(ele,index){ele.className = 'white';})
}var start_index = 0;function left(){pre_ul_ele.style.transition = 'all 0.5s';let left_v = parseInt(pre_ul_ele.style.left);pre_ul_ele.style.left = left_v - 500 + 'px';clear_red();start_index = (start_index+1)%n;dots[start_index].className = 'red';if(left_v - 500 == -n*img_width){pre_ul_ele.style.left = 0;}
}var timer1 = setInterval(left,2000);注：上述代碼沒有給出點擊按鈕變化圖片特效，想實現(xiàn)的讀者可以去看看上述第一個關于實現(xiàn)輪播圖的版本哈！