JS单个、批量下载图片

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8" />
        <title></title>
    </head>
    <body>
        <!-- 通过<a>链接来实现图片下载 -->
        <a href="img/image1.jpg" download="down">
            <img src="img/image1.jpg" alt="" width="200px" height="100px">
        </a>


        <!-- 通过JS来触发<a>链接来实现图片下载 -->
        <img id="down" src="img/image1.jpg" alt="" width="200px" height="100px">
        <button class="downloadBtn" type="button" onclick="downloadImg()">下载图片</button>
        
        
        <!-- 批量下载图片 -->
        <script src="http://stuk.github.io/jszip/test/jquery-1.8.3.min.js"></script>
        <script type="text/javascript" src="https://stuk.github.io/jszip/dist/jszip.js"></script>
        <script type="text/javascript" src="http://stuk.github.io/jszip/vendor/FileSaver.js"></script>
        
        <img src="img/image1.jpg" alt="" width="200px" height="100px">
        <img src="img/image2.jpg" alt="" width="200px" height="100px">
        <button onclick="packageImages()">packageImages</button><span id="status"></span>
    </body>
    <script>
        //单个下载
        function downloadImg(){
                var img = document.getElementById('down'); // 获取要下载的图片
                var url = img.src;                            // 获取图片地址
                var a = document.createElement('a');          // 创建一个a节点插入的document
                var event = new MouseEvent('click')           // 模拟鼠标click点击事件
                a.download = 'image'                          // 设置a节点的download属性值
                a.href = url;                                 // 将图片的src赋值给a节点的href
                a.dispatchEvent(event)                        // 触发鼠标点击事件
             }
             
             
        //批量下载
        function packageImages() {
            $('#status').text('处理中。。。。。');
        
            var imgs = $('img');
        
            var imgsSrc = [];
            var imgBase64 = [];
            var imageSuffix = [];//图片后缀
            var zip = new JSZip();
            // zip.file("readme.txt", "案件详情资料
");
            var img = zip.folder("images");
        
            for (var i = 0; i < imgs.length; i++) {
                var src = imgs[i].getAttribute("src");
                var suffix = src.substring(src.lastIndexOf("."));
                imageSuffix.push(suffix);
        
                getBase64(imgs[i].getAttribute("src"))
                    .then(function (base64) {
                        imgBase64.push(base64.split(",")[1]);
        
                        //console.log(base64);//处理成功打印在控制台
                    }, function (err) {
                        console.log(err);//打印异常信息
                    });
        
            }
            function tt() {
                setTimeout(function () {
                    if (imgs.length == imgBase64.length) {
                        for (var i = 0; i < imgs.length; i++) {
                            img.file(i + imageSuffix[i], imgBase64[i], { base64: true });
                        }
                        zip.generateAsync({ type: "blob" }).then(function (content) {
                            // see FileSaver.js
                            saveAs(content, "images.zip");
                        });
                        $('#status').text('处理完成。。。。。');
        
                    } else {
                        //console.log('imgs.length:'+imgs.length+',imgBase64.length:'+imgBase64.length);
                        $('#status').text('已完成:' + imgBase64.length + '/' + imgs.length);
                        tt();
                    }
                }, 100);
        
            }
            tt();
        }
        //传入图片路径,返回base64
        function getBase64(img) {
            function getBase64Image(img, width, height) {//width、height调用时传入具体像素值,控制大小 ,不传则默认图像大小
                var canvas = document.createElement("canvas");
                canvas.width = width ? width : img.width;
                canvas.height = height ? height : img.height;
        
                var ctx = canvas.getContext("2d");
                ctx.drawImage(img, 0, 0, canvas.width, canvas.height);
                var dataURL = canvas.toDataURL();
                return dataURL;
            }
            var image = new Image();
            image.crossOrigin = 'Anonymous';
            image.src = img;
            var deferred = $.Deferred();
            if (img) {
                image.onload = function () {
                    deferred.resolve(getBase64Image(image));//将base64传给done上传处理
                }
                return deferred.promise();//问题要让onload完成后再return sessionStorage['imgTest']
            }
        }
    </script>
</html>

原文地址:https://www.cnblogs.com/MoooJL/p/14743628.html