JarCastingCompressor.js
JavaScript image compressor. Uses the Browser's native canvas.toBlob API to do the compression work, which means it is lossy compression. General use this to precompress a client image file before upload it.
Table of contents
Main
dist/
├── compressor.js (UMD)
├── compressor.min.js (UMD, compressed)
├── compressor.common.js (CommonJS, default)
└── compressor.esm.js (ES Module)
Getting started
Install
npm install compressorjs
Usage
Syntax
new Compressor(file[, options])
file
The target image file for compressing.
options
- Type:
Object - Optional
The options for compressing. Check out the available options.
Example
<input type="file" id="file" accept="image/*">
import axios from 'axios';
import Compressor from 'compressorjs';
document.getElementById('file').addEventListener('change', (e) => {
const file = e.target.files[0];
if (!file) {
return;
}
new Compressor(file, {
quality: 0.6,
success(result) {
const formData = new FormData();
// The third parameter is required for server
formData.append('file', result, result.name);
// Send the compressed image file to server with XMLHttpRequest.
axios.post('/path/to/upload', formData).then(() => {
console.log('Upload success');
});
},
error(err) {
console.log(err.message);
},
});
});
Options
You may set compressor options with new Compressor(file, options). If you want to change the global default options, You may use Compressor.setDefaults(options).
strict
- Type:
boolean - Default:
true
Indicates if output the original image instead of the compressed one when the size of the compressed image is greater than the original one's, except the following cases:
- The
mimeTypeoption is set and its value is different from the mime type of the image. - The
widthoption is set and its value is greater than the natural width of the image. - The
heightoption is set and its value is greater than the natural height of the image. - The
minWidthoption is set and its value is greater than the natural width of the image. - The
minHeightoption is set and its value is greater than the natural height of the image.
checkOrientation
- Type:
boolean - Default:
true
Indicates if read the image's Exif Orientation value (JPEG image only), and then rotate or flip the image automatically with the value.
Notes:
- Don't trust this all the time as some JPEG images have incorrect (not standard) Orientation values.
- If the size of target image is too large (e.g., greater than 10 MB), you should disable this option to avoid out-of-memory crash.
maxWidth
- Type:
number - Default:
Infinity
The max width of the output image. The value should be greater than 0.
Avoid to get a blank output image, you might need to set the
maxWidthandmaxHeightoptions to limited numbers, because of the size limits of a canvas element, recommend to use4096or lesser.
maxHeight
- Type:
number - Default:
Infinity
The max height of the output image. The value should be greater than 0.
minWidth
- Type:
number - Default:
0
The min width of the output image. The value should be greater than 0 and should not be greater than the maxWidth.
minHeight
- Type:
number - Default:
0
The min height of the output image. The value should be greater than 0 and should not be greater than the maxHeight.
width
- Type:
number - Default:
undefined
The width of the output image. If not specified, the natural width of the original image will be used, or if the height option is set, the width will be computed automatically by the natural aspect ratio.
height
- Type:
number - Default:
undefined
The height of the output image. If not specified, the natural height of the original image will be used, or if the width option is set, the height will be computed automatically by the natural aspect ratio.
quality
- Type:
number - Default:
0.8
The quality of the output image. It must be a number between 0 and 1. If this argument is anything else, the default values 0.92 and 0.80 are used for image/jpeg and image/webp respectively. Other arguments are ignored. Be careful to use 1 as it may make the size of the output image become larger.
Note: This option only available for image/jpeg and image/webp images.
Check out canvas.toBlob for more detail.
Examples:
| Quality | Input size | Output size | Compression ratio | Description |
|---|---|---|---|---|
| 0 | 2.12 MB | 114.61 KB | 94.72% | - |
| 0.2 | 2.12 MB | 349.57 KB | 83.90% | - |
| 0.4 | 2.12 MB | 517.10 KB | 76.18% | - |
| 0.6 | 2.12 MB | 694.99 KB | 67.99% | Recommend |
| 0.8 | 2.12 MB | 1.14 MB | 46.41% | Recommend |
| 1 | 2.12 MB | 2.12 MB | 0% | Not recommend |
| NaN | 2.12 MB | 2.01 MB | 5.02% | - |
mimeType
- Type:
string - Default:
'auto'
The mime type of the output image. By default, the original mime type of the source image file will be used.
convertSize
- Type:
number - Default:
5000000(5 MB)
PNG files over this value will be converted to JPEGs. To disable this, just set the value to Infinity.
Examples:
| convertSize | Input size (type) | Output size (type) | Compression ratio |
|---|---|---|---|
| 5 MB | 1.87 MB (PNG) | 1.87 MB (PNG) | 0% |
| 5 MB | 5.66 MB (PNG) | 450.24 KB (JPEG) | 92.23% |
| 5 MB | 9.74 MB (PNG) | 883.89 KB (JPEG) | 91.14% |
beforeDraw(context, canvas)
- Type:
Function - Default:
null - Parameters:
context: The 2d rendering context of the canvas.canvas: The canvas for compression.
The hook function to execute before draw the image into the canvas for compression.
new Compressor(file, {
beforeDraw(context, canvas) {
context.fillStyle = '#fff';
context.fillRect(0, 0, canvas.width, canvas.height);
context.filter = 'grayscale(100%)';
},
});
drew(context, canvas)
- Type:
Function - Default:
null - Parameters:
context: The 2d rendering context of the canvas.canvas: The canvas for compression.
The hook function to execute after drew the image into the canvas for compression.
new Compressor(file, {
drew(context, canvas) {
context.fillStyle = '#fff';
context.font = '2rem serif';
context.fillText('watermark', 20, canvas.height - 20);
},
});
success(result)
- Type:
Function - Default:
null - Parameters:
result: The compressed image (aFile(read only) orBlobobject).
The hook function to execute when success to compress the image.
error(err)
- Type:
Function - Default:
null - Parameters:
err: The compression error (anErrorobject).
The hook function to execute when fail to compress the image.
Methods
abort()
Abort the compression process.
const compressor = new Compressor(file);
// Do something...
compressor.abort();
No conflict
If you have to use other compressor with the same namespace, just call the Compressor.noConflict static method to revert to it.
<script src="other-compressor.js"></script>
<script src="compressor.js"></script>
<script>
Compressor.noConflict();
// Code that uses other `Compressor` can follow here.
</script>
Browser support
- Chrome (latest)
- Firefox (latest)
- Safari (latest)
- Opera (latest)
- Edge (latest)
- Internet Explorer 10+
Contributing
Please read through our contributing guidelines.
Versioning
Maintained under the Semantic Versioning guidelines.