javascript - 检查文件扩展名，如果不是图像文件则提醒用户

Question

我需要帮助来添加一些代码来检查文件是否是图像，以检查扩展名。这是我用来指示上传图片进度的代码。我在 php 中这样做，用户不能上传任何文件，除了 .jpg .jpeg .gif 和 .png 但他没有收到文件未上传的消息。当我为进度上传添加 javascript 代码时，我创建的 php 消息不再显示。

这是我的javascript upload.js文件代码:

 var handleUpload = function(event) {
    event.preventDefault();
    event.stopPropagation();

    var fileInput = document.getElementById('image_id');

    var data = new FormData();

    data.append('javascript', true);

        if(fileInput.files[0].size > 1050000) {
        document.getElementById("image_id").innerHTML = "Image too big (max 1Mb)";
        alert('Fotografija koju želite dodati je veća od 1Mb!');
        window.location="upload_images.php"
        return false;
        }

    for (var i =0; i < fileInput.files.length; ++i) {
        data.append('image', fileInput.files[i]);
    }

    var request = new XMLHttpRequest();

    request.upload.addEventListener('progress', function(event) {
        if (event.lengthComputable) {
            var percent = event.loaded / event.total;
            var progress = document.getElementById('upload_progress');

            while (progress.hasChildNodes()) {
                progress.removeChild(progress.firstChild);
            }

            progress.appendChild(document.createTextNode(Math.round(percent * 100) + ' %'));
        }
    });

    request.upload.addEventListener('load', function(event) {
        document.getElementById('upload_progress').style.display = 'none';
    });

    request.upload.addEventListener('error', function(event) {
        alert('Dodavanje slika nije bilo uspješno! Pokušajte ponovo.');
    });

    request.addEventListener('readystatechange', function(event) {

        if (this.readyState == 4) {
            if(this.status == 200) {
                var links = document.getElementById('uploaded');

                window.location="upload_images.php?success"
                console.log(this.response); 
            } else {
                console.log('Server replied with HTTP status ' + this.status);
            }
        }

    });

    request.open('POST', 'upload_images.php');
    request.setRequestHeader('Cache-Control', 'no-cache');

    document.getElementById('upload_progress').style.display = 'block';

    request.send(data);
}

window.addEventListener('load', function(event) {
    var submit = document.getElementById('submit');
    submit.addEventListener('click', handleUpload);

});

这是我上传文件的表格:

<div id="uploaded">

</div>
<div>
<form action="" method="post" enctype="multipart/form-data">
<input name="image" id="image_id" type="file" size="25" value="Odaberi sliku" />
<input type="submit" id="submit" value="Dodaj Foto"/>
</form>
</div>
<div class="upload_progress" id="upload_progress"></div>

我还需要在那个 javascript 代码中检查文件是图像。允许 jpg、jpeg、png 和 gif 扩展名并阻止其他扩展名。提醒用户是否尝试上传其他类型的文件。

Answer 1

if (!fileInput.files[0].name.match(/\.(jpg|jpeg|png|gif)$/i))
    alert('not an image');