Home > Article > Web Front-end > How does JavaScript use DOM to switch images?

How does JavaScript use DOM to switch images?

不言Original: 2018-07-21 09:54:012434browse

This article shares with you how to use JavaScript to switch images using DOM? , the content is very good, friends in need can refer to it, I hope it can help everyone.

Start learning DOM operations today. Let’s write a small case to consolidate the knowledge points.

DOM: document object model

According to id Get page elements: For example: var xx = document.getElementById("id");

Get elements based on tag: For example: var xx = document .getElementsB##yTagName("p");

src="imgs/1.png"/><br>    <button id="btn1" type="button" value="

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        #outer {
            width: 500px;
            /*设置上边距50px 水平居中*/
            margin: 50px auto;
            /*设置边框*/
            padding: 10px;
            background-color: greenyellow;
            /*设置文本居中*/
            text-align: center;
        }

        img {
            width: 500px;
        }
    </style>


    <script>
　　　　　//btn 为按钮id   clickEventFunction 为点击后执行的操作函数
        function addClick(btn, clickEventFunction) {
            var myButton = document.getElementById(btn);
            myButton.onclick = clickEventFunction;
        };

        window.onload = function () {
            (function () {
                var pics = ["imgs/1.png",
                    "imgs/2.png",
                    "imgs/3.png"];
                var index = 0;
                showPicNum(index);
                var img = document.getElementsByTagName("img")[0];

                // var btn1 = document.getElementById("btn1");
                var btn2 = document.getElementById("btn2");
                addClick("btn1", function () {
                    index--;
                    if (index <= -1) {
                        index = pics.length - 1;
                    }
                    console.log(index + " ----- ");
                    img.src = pics[index];
                    showPicNum(index);
                });
                addClick("btn2", function () {
                    index++;
                    if (index >= pics.length) {
                        index = 0;
                    }
                    console.log(index + " ++++++++ ");
                    img.src = pics[index];
                    showPicNum(index);
                });

                //
                // btn1.onclick = function () {
                //     index --;
                //     if(index <= -1){
                //         index = pics.length - 1;
                //     }
                //     console.log(index  + " ----- ");
                //     img.src = pics[index];
                //     showPicNum(index);
                // };
                // btn2.onclick = function () {
                //     index ++;
                //     if(index >= pics.length){
                //         index = 0;
                //     }
                //     console.log(index  + " ++++++++ ");
                //     img.src = pics[index];
                //     showPicNum(index);
                // };
                console.log(index);

                /**
                 * 展示当前图片为第几张
                 * @param index   当前图片索引
                 */
                function showPicNum(index) {
                    var descrs = document.getElementById("discs");
                    descrs.innerText = "一共" + pics.length + "张图片,当前第" + ++index + "张";
                }
            }())
        };
    </script>
</head>
<body>
<div id="outer">
    <p id="discs"></p>
    <img src="imgs/1.png"/><br>
    <button id="btn1" type="button" value="上一张">上一张</button>
    <button id="btn2" type="button" value="下一张">下一张</button>
</div>
</body>
</html>

Document directory:

The effect is as follows:

上一张">上一张</button>    <button id="btn2" type="button" value="下一张">下一张</button></div></body></html>

Related recommendations:

Further analysis of JS scope and object-oriented

How js implements the method of uploading and compressing images

The above is the detailed content of How does JavaScript use DOM to switch images?. For more information, please follow other related articles on the PHP Chinese website!

Statement：

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Previous article：How to define an array in js? Summary of the definition and operation examples of arrays in jsNext article：How to define an array in js? Summary of the definition and operation examples of arrays in js

See more

How does JavaScript use DOM to switch images?

Related articles