Customize the style of input[type='file']

The style of input[type="file"] behaves differently in various browsers:

1.chrome:

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2.firefox:

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3. opera:

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4.ie:

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5.edge:

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In addition, when we specify the height of input[type="file"] and set its line height to be equal to its height, an ugly style appears in chrome:

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The line "No files selected" is not centered vertically.

It seems to look better in firefox. Well, I prefer using firefox. However, the performance in these browsers is inconsistent, and we must do compatibility processing.

Idea:

1. Customize a style similar to one of the browsers and put it on the lower layer;

2. "Hide" the style displayed by the browser itself, and place opacity: 0; on the upper layer, so that what we click is the event that input[type="file"] responds to;

3. After selecting a file or changing a file, change the value of displayed file.

Code:

html:
<form action="" class="activityForm">
　　<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>
</form>

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;
}

After processing in this way, the performance will be consistent in various browsers:

1. In chrome when no file is selected:

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2. After selecting the file, in firefox: