html
<div class="file">
<label for="file">文件：</label>
<div class="userdefined-file">
<input type="text" name="userdefinedFile" id="userdefinedFile" value="未选择任何文件">
<button type="button">上传</button>
</div>
<input type="file" name="file" id="file">
</div>
css
.file {
position: relative;
height: 40px;
line-height: 40px;
}
.file label {
display: inline-block;
}
.userdefined-file {
position: absolute;
top: 0;
left: 60px;
z-index: 2;
width: 300px;
height: 40px;
line-height: 40px;
font-size: 0; /*应对子元素为 inline-block 引起的外边距*/
}
.userdefined-file input[type="text"] {
display: inline-block;
vertical-align: middle;
padding-right: 14px;
padding-left: 14px;
width: 220px;
box-sizing: border-box;
border: 1px solid #ccc;
height: 40px;
line-height: 40px;
font-size: 14px;
overflow: hidden;
text-overflow: ellipsis;
white-space: nowrap;
}
.userdefined-file button {
display: inline-block;
vertical-align: middle;
width: 80px;
text-align: center;
height: 40px;
line-height: 40px;
font-size: 14px;
background-color: #f54;
border: none;
color: #fff;
cursor: pointer;
}
.file input[type="file"] {
position: absolute;
top: 0;
left: 60px;
z-index: 3;
opacity: 0;
width: 300px;
height: 40px;
line-height: 40px;
cursor: pointer;
}
js
document.getElementById("file").onchange = function() {
document.getElementById("userdefinedFile").value = document.getElementById("file").value;
}