INPUT FILE实现前端验证文件类型和大小限制和图片长宽限制
现代浏览器越来越强大，以前限制文件上传类型和大小要使用flash，现在html5直接支持，input file可以在chrome浏览器实现文件类型过滤及大小限制了,我们来看看示例
<input type="file" accept="image/*" />上面那段代码就是加了accept属性
accept表示可以上传文件类型，image表示图片，*表示所有支持的格式。
下面我们来看看input accept支持哪些类型
| *.3gpp | audio/3gpp, video/3gpp | 3GPP Audio/Video |
| *.ac3 | audio/ac3 | AC3 Audio |
| *.asf | allpication/vnd.ms-asf | Advanced Streaming Format |
| *.au | audio/basic | AU Audio |
| *.css | text/css | Cascading Style Sheets |
| *.csv | text/csv | Comma Separated Values |
| *.doc | application/msword | MS Word Document |
| *.dot | application/msword | MS Word Template |
| *.dtd | application/xml-dtd | Document Type Definition |
| *.dwg | image/vnd.dwg | AutoCAD Drawing Database |
| *.dxf | image/vnd.dxf | AutoCAD Drawing Interchange Format |
| *.gif | image/gif | Graphic Interchange Format |
| *.htm | text/html | HyperText Markup Language |
| *.html | text/html | HyperText Markup Language |
| *.jp2 | image/jp2 | JPEG-2000 |
| *.jpe | image/jpeg | JPEG |
| *.jpeg | image/jpeg | JPEG |
| *.jpg | image/jpeg | JPEG |
| *.js | text/javascript, application/javascript | JavaScript |
| *.json | application/json | JavaScript Object Notation |
| *.mp2 | audio/mpeg, video/mpeg | MPEG Audio/Video Stream, Layer II |
| *.mp3 | audio/mpeg | MPEG Audio Stream, Layer III |
| *.mp4 | audio/mp4, video/mp4 | MPEG-4 Audio/Video |
| *.mpeg | video/mpeg | MPEG Video Stream, Layer II |
| *.mpg | video/mpeg | MPEG Video Stream, Layer II |
| *.mpp | application/vnd.ms-project | MS Project Project |
| *.ogg | application/ogg, audio/ogg | Ogg Vorbis |
| application/pdf | Portable Document Format | |
| *.png | image/png | Portable Network Graphics |
| *.pot | application/vnd.ms-powerpoint | MS PowerPoint Template |
| *.pps | application/vnd.ms-powerpoint | MS PowerPoint Slideshow |
| *.ppt | application/vnd.ms-powerpoint | MS PowerPoint Presentation |
| *.rtf | application/rtf, text/rtf | Rich Text Format |
| *.svf | image/vnd.svf | Simple Vector Format |
| *.tif | image/tiff | Tagged Image Format File |
| *.tiff | image/tiff | Tagged Image Format File |
| *.txt | text/plain | Plain Text |
| *.wdb | application/vnd.ms-works | MS Works Database |
| *.wps | application/vnd.ms-works | Works Text Document |
| *.xhtml | application/xhtml+xml | Extensible HyperText Markup Language |
| *.xlc | application/vnd.ms-excel | MS Excel Chart |
| *.xlm | application/vnd.ms-excel | MS Excel Macro |
| *.xls | application/vnd.ms-excel | MS Excel Spreadsheet |
| *.xlt | application/vnd.ms-excel | MS Excel Template |
| *.xlw | application/vnd.ms-excel | MS Excel Workspace |
| *.xml | text/xml, application/xml | Extensible Markup Language |
| *.zip | application/zip | Compressed Archive |
那么也可以通过js读取file来验证过滤文件类型
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>BFW NEW PAGE</title>
<script id="bfwone" data="dep=jquery.17&err=0" type="text/javascript" src="http://repo.bfw.wiki/bfwrepo/js/bfwone.js"></script>
<script type="text/javascript">
bready(function() {
$('#upload-file').change(function() {
console.log(this.files[0]);
})
});
</script>
</head>
<body>
<input type="file" id="upload-file" accept="image/*" />
</body>
</html>上面的代码执行完我们会发现file有一些属性，name,size,type,lastmodifieddate
可以通过这些属性来验证大小和类型
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>BFW NEW PAGE</title>
<script id="bfwone" data="dep=jquery.17&err=0" type="text/javascript" src="http://repo.bfw.wiki/bfwrepo/js/bfwone.js"></script>
<script type="text/javascript">
bready(function() {
$('#upload-file').change(function() {
console.log(this.files[0]);
var fileSize = (this.files[0].size / 1024).toFixed(0);
var fileType = this.files[0].type;
if (fileSize > 2000) {
alert('文件过大，不能超过2000kb');
}
if (fileType != "image/png") {
alert('文件类型为png');
}
});
});
</script>
</head>
<body>
<input type="file" id="upload-file" accept="image/*" />
</body>
</html>还可以验证图片的长宽
var reader = new FileReader();
reader.onload = function (e) {
var data = e.target.result;
//加载图片获取图片真实宽度和高度
var image = new Image();
image.onload = function() {
var width = image.width;
var height = image.height;
if (_width != 0) {
if (width != _width) {
alert("图片宽度应该为！"+_width+"像素");
return false;
}
}
if (_height != 0) {
if (height != _height) {
alert("图片高度应该为！"+_height+"像素");
return false;
}
}
callback();
};
image.src = data;
};
reader.readAsDataURL(file);完整的例子如下：
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>BFW NEW PAGE</title>
<script id="bfwone" data="dep=jquery.17&err=0" type="text/javascript" src="http://repo.bfw.wiki/bfwrepo/js/bfwone.js"></script>
<script type="text/javascript">
/**
*
* @param {this} value_ [获取input对象，一般为this]
* @param {[number]} size_ [文件限制的大小，单位为kb]
* @param {[string]} type_ [文件类型，当前支持image和office]
*@param {[number]} width [图片宽度，0为不限制]
*@param {[number]} height [图片高度，0为不限制]
* @param {[function]} callback [验证通过的回调]
*/
function validfile (value_, size_, type_, _width, _height, callback) {
var file = value_.files[0]
var fileSize = (file.size / 1024).toFixed(0)
var fileType = value_.value.substring(value_.value.lastIndexOf("."))
if (fileSize > size_) {
alert('文件过大，不能超过'+size_+"kb");
return false;
}
switch (type_) {
case 'image':
if (!fileType.match(/.jpg|.jpeg|.gif|.png|.bmp/i)) {
alert('请上传图片')
return false;
}
var reader = new FileReader();
reader.onload = function (e) {
var data = e.target.result;
//加载图片获取图片真实宽度和高度
var image = new Image();
image.onload = function() {
var width = image.width;
var height = image.height;
if (_width != 0) {
if (width != _width) {
alert("图片宽度应该为！"+_width+"像素");
return false;
}
}
if (_height != 0) {
if (height != _height) {
alert("图片高度应该为！"+_height+"像素");
return false;
}
}
callback();
};
image.src = data;
};
reader.readAsDataURL(file);
break;
case 'office':
if (!fileType.match(/.doc|.docx|.xls|.xlsx|.ppt|.pptx/i)) {
alert('请上传word、excel或ppt文件')
return false;
}
callback();
break;
default:
console.error('type_参数设置不正确！')
return false;
break;
}
}
bready(function() {
$('#upload-file').change(function() {
validfile(this, 2000, 'image', 0, 0, function() {
alert('验证成功')
})
})
});
</script>
</head>
<body>
<input type="file" id="upload-file" accept="image/*" />
</body>
</html>
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