这是一种非常简单的纯css创建自定义输入文件的方法。

使用标签，但是从前面的回答中可以知道，标签不会调用onclick firefox中的函数，可能是一个bug，但与以下内容无关。

<label for="file"  class="custom-file-input"><input type="file"  name="file" class="custom-file-input"></input></label>

你要做的就是将标签样式设置成你想要的样子

    .custom-file-input {
        color: transparent;/* This is to take away the browser text for file uploading*/
        /* Carry on with the style you want */
        background: url(../img/doc-o.png);
        background-size: 100%;
        position: absolute;
        width: 200px;
        height: 200px;
        cursor: pointer;
        top: 10%;
        right: 15%;
    }

现在简单地隐藏实际的输入按钮，但你不能将其设置为可见:隐藏

所以通过设置不透明度:0来让它不可见;

input.custom-file-input {
    opacity: 0;
    position: absolute;/*set position to be exactly over your input*/
    left: 0;
    top: 0;
}

现在，你可能已经注意到，我在标签上有和输入字段相同的类，这是因为我希望两者具有相同的样式，因此，无论你在哪里点击标签，你实际上是在点击不可见的输入字段。

诀窍是在点击文件输入时触发一个点击事件，并通过CSS管理默认输入文件的可见性。你可以这样做: jQuery:

$(function() {
  $("#labelfile").click(function() {
    $("#imageupl").trigger('click');
  });
})

css

.file {
  position: absolute;
  clip: rect(0px, 0px, 0px, 0px);
  display: block;
}

.labelfile {
  color: #333;
  background-color: #fff;
  display: inline-block;
  margin-bottom: 0;
  font-weight: 400;
  text-align: center;
  vertical-align: middle;
  cursor: pointer;
  background-image: none;
  white-space: nowrap;
  padding: 6px 8px;
  font-size: 14px;
  line-height: 1.42857143;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
}

HTML代码:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<div>
  <input name="imageupl" type="file" id="imageupl" class="file" />
  <label class="labelfile" id="labelfile"><i class="icon-download-alt"></i> Browse File</label>
</div>

我的解决方案…

HTML:

<input type="file" id="uploadImages" style="display:none;" multiple>

<input type="button" id="callUploadImages" value="Select">
<input type="button" id="uploadImagesInfo" value="0 file(s)." disabled>
<input type="button" id="uploadProductImages" value="Upload">

Jquery:

$('#callUploadImages').click(function(){

    $('#uploadImages').click();
});

$('#uploadImages').change(function(){

    var uploadImages = $(this);
    $('#uploadImagesInfo').val(uploadImages[0].files.length+" file(s).");
});

这是邪恶的:D

为了实现这一点，默认的输入按钮必须使用display:none CSS属性隐藏，并添加一个新的按钮元素来替换它，因此我们可以根据需要进行定制。

与引导

<link rel=“stylesheet” href=“https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css”> 此处为可选文本 <label for=“img” class=“btn btn-info”>试试我</label> <输入类型=“文件” id=“img” 样式=“显示：无”>

与jQuery

在本例中，添加到button元素的onclick属性指示JavaScript在单击可见按钮时单击隐藏的默认输入按钮。

<script src=“https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js”></script> 此处为可选文本 <button style=“cursor：pointer” onclick=“$（'#input'）.click（）”>Click me</button> <输入类型=“文件” id=“输入” 样式=“显示：无”>

简单的JavaScript事件监听器

. getelementbyid (btn)。addEventListener('click'， () => { . getelementbyid(“输入”).click (); }) 此处可选文本 <button style="cursor:pointer" id="btn">点击我</button> <input type="file" id="input" style="display:none">

Below is an example of a stylized upload button that will read an image, compress it, and download the resulting image. It works by hiding the actual input element, and then through some trickery we make it so that when you click on our fake file uploader it uses the actual input element to pop up the window for choosing a file. By using this method we get 100% control over how the file uploader looks since we are using our own element instead of styling the file upload menu. It also makes it easy to add drag and drop functionality in the future if we ever want to do that.

然后我写了一系列关于这个文件上传按钮的博文。

'use strict' var AMOUNT = 10 var WIDTH = 600 var HEIGHT = 400 var canvas = document.getElementById('canvas') canvas.width = WIDTH canvas.height = HEIGHT //here's how I created the clickable area //user clicks the clickable area > we send a click event //to the file opener > the file opener clicks on the open //file button > the open file dialogue pops up function clickableAreaListener(e){ let clickEvent = new CustomEvent("click",{"from":"fileOpenerHandler"}); document.getElementById("fileOpener").dispatchEvent(clickEvent); } function fileOpenerListener(e) { document.getElementById("file-btn").click(); e.preventDefault(); } function fileSelectedListener(e){ readFiles(e.target.files); } document.getElementById('file-btn').addEventListener('change', fileSelectedListener); document.getElementById("clickable-area").addEventListener('click', clickableAreaListener); document.getElementById("fileOpener").addEventListener("click", fileOpenerListener); function readFiles(files){ files = [].slice.call(files); //turning files into a normal array for (var file of files){ var reader = new FileReader(); reader.onload = createOnLoadHandler(file); reader.onerror = fileErrorHandler; //there are also reader.onloadstart, reader.onprogress, and reader.onloadend handlers reader.readAsDataURL(file); } } function fileErrorHandler(e) { switch(e.target.error.code) { case e.target.error.NOT_FOUND_ERR: throw 'Image not found'; break; case e.target.error.NOT_READABLE_ERR: throw 'Image is not readable'; break; case e.target.error.ABORT_ERR: break; default: throw 'An error occurred while reading the Image'; }; } function createOnLoadHandler(file){ console.log('reading ' + file.name + ' of type ' + file.type) //file.type will be either image/jpeg or image/png function onLoad(e){ var data = e.target.result display(data); var compressedData = compressCanvas(AMOUNT) download(compressedData) } return onLoad } function display(data){ var img = document.createElement('img'); img.src = data; var context = canvas.getContext('2d') context.clearRect(0, 0, WIDTH, HEIGHT); context.drawImage(img, 0, 0, WIDTH, HEIGHT); } function compressCanvas(){ return canvas.toDataURL('image/jpeg', AMOUNT / 100); } function download(data) { function b64toBlob(b64Data, contentType, sliceSize) { contentType = contentType || ''; sliceSize = sliceSize || 512; var byteCharacters = atob(b64Data); var byteArrays = []; for (var offset = 0; offset < byteCharacters.length; offset += sliceSize) { var slice = byteCharacters.slice(offset, offset + sliceSize); var byteNumbers = new Array(slice.length); for (var i = 0; i < slice.length; i++) { byteNumbers[i] = slice.charCodeAt(i); } var byteArray = new Uint8Array(byteNumbers); byteArrays.push(byteArray); } var blob = new Blob(byteArrays, {type: contentType}); return blob; } var chromeApp = Boolean(chrome && chrome.permissions) if (chromeApp){ chrome.fileSystem.chooseEntry({type:'openDirectory'}, function(entry) { chrome.fileSystem.getWritableEntry(entry, function(entry) { entry.getFile('example.jpg', {create:true}, function(entry) { entry.createWriter(function(writer){ writer.write(b64toBlob(data.slice(23), 'image/jpg')) }) }) }) }) } else { let a = document.createElement("a"); a.href = data; a.download = 'downloadExample.jpg' document.body.appendChild(a) a.click(); window.URL.revokeObjectURL(a.href); a.remove() } } .fileInput { display: none; position: absolute; top: 0; right: 0; font-size: 100px; } #clickable-area{ background: #ccc; width: 500px; display: flex; margin-bottom: 50px; } #clickable-area-text{ margin: auto; } .yellow-button { cursor: pointer; color: white; background: #f1c40f; height: 30px; width: 120px; padding: 30px; font-size: 22px; text-shadow: 0 1px 2px rgba(0, 0, 0, 0.25); } <div id="clickable-area"> <a id='fileOpener'> </a> <input type="file" class="fileInput" id="file-btn" accept="image/*" multiple/> <div class="yellow-button"><span>Shrink Image</span> </div><p id="clickable-area-text">( you can click anywhere in here ) &nbsp;</p> </div> <canvas id="canvas"></canvas>

Stack Overflow的限制似乎阻止了代码片段实际压缩和下载文件。这里完全相同的代码显示了完整的上传/压缩/下载过程实际上按预期工作。

这应该可以工作:

input.*className*::-webkit-file-upload-button {
  *style content..*
}