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 Administrator
finish work part 1
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# JavaScript Canvas to Blob
## Description
Canvas to Blob is a polyfill for the standard JavaScript
[canvas.toBlob](http://www.w3.org/TR/html5/scripting-1.html#dom-canvas-toblob)
method.
It can be used to create
[Blob](https://developer.mozilla.org/en-US/docs/Web/API/Blob)
objects from an HTML
[canvas](https://developer.mozilla.org/en-US/docs/HTML/Canvas) element.
## Usage
Include the (minified) JavaScript Canvas to Blob script in your HTML markup:
```html
<script src="js/canvas-to-blob.min.js"></script>
```
Then use the *canvas.toBlob()* method in the same way as the native
implementation:
```js
var canvas = document.createElement('canvas');
/* ... your canvas manipulations ... */
if (canvas.toBlob) {
canvas.toBlob(
function (blob) {
// Do something with the blob object,
// e.g. creating a multipart form for file uploads:
var formData = new FormData();
formData.append('file', blob, fileName);
/* ... */
},
'image/jpeg'
);
}
```
## Requirements
The JavaScript Canvas to Blob function has zero dependencies.
However, Canvas to Blob is a very suitable complement to the
[JavaScript Load Image](https://github.com/blueimp/JavaScript-Load-Image)
function.
## API
In addition to the **canvas.toBlob** polyfill, the JavaScript Canvas to Blob
script provides one additional function called **dataURLtoBlob**, which is added
to the global window object, unless the library is loaded via a module loader
like RequireJS, Browserify or webpack:
```js
// 80x60px GIF image (color black, base64 data):
var b64Data = 'R0lGODdhUAA8AIABAAAAAP///ywAAAAAUAA8AAACS4SPqcvtD6' +
'OctNqLs968+w+G4kiW5omm6sq27gvH8kzX9o3n+s73/g8MCofE' +
'ovGITCqXzKbzCY1Kp9Sq9YrNarfcrvcLDovH5PKsAAA7',
imageUrl = 'data:image/gif;base64,' + b64Data,
blob = window.dataURLtoBlob && window.dataURLtoBlob(imageUrl);
```
## Browsers
The following browsers support either the native or the polyfill
*canvas.toBlob()* method:
### Desktop browsers
* Google Chrome (see [Chromium issue #67587](https://code.google.com/p/chromium/issues/detail?id=67587))
* Apple Safari 6.0+ (see [Mozilla issue #648610](https://bugzilla.mozilla.org/show_bug.cgi?id=648610))
* Mozilla Firefox 4.0+
* Microsoft Internet Explorer 10.0+
### Mobile browsers
* Apple Safari Mobile on iOS 6.0+
* Google Chrome on iOS 6.0+
* Google Chrome on Android 4.0+
## Test
[JavaScript Canvas to Blob Test](https://blueimp.github.io/JavaScript-Canvas-to-Blob/test/)
## License
The JavaScript Canvas to Blob script is released under the
[MIT license](http://www.opensource.org/licenses/MIT).
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