GitHub - kevinAlbs/Base122: A space efficient alternative to base-64 (original) (raw)
Base-122 Encoding
A space efficient UTF-8 binary-to-text encoding created as an alternative to base-64 in data URIs. Base-122 is ~14% smaller than equivalent base-64 encoded data. Details of motivation and implementation can be found on this article.
Base-122 is currently an experimental encoding, and may undergo changes.
Basic Usage
Base-122 encoding produces UTF-8 characters, but encodes more bits per byte than base-64.
let base122 = require('./base122'); let inputData = require('fs').readFileSync('example.jpg') let base64Encoded = inputData.toString('base64'); let base122Encoded = Buffer.from(base122.encode(inputData), 'utf8');
console.log("Original size = " + inputData.length); // Original size = 1429 console.log("Base-64 size = " + base64Encoded.length); // Base-64 size = 1908 console.log("Base-122 size = " + base122Encoded.length); // Base-122 size = 1635 console.log("Saved " + (base64Encoded.length - base122Encoded.length) + " bytes") // Saved 273 bytes
Note, even though base-122 produces valid UTF-8 characters, control characters aren't always preserved when copy pasting. Therefore, encodings should be saved to files through scripts, not copy-pasting. Here is an example of saving base-122 to a file:
let base122 = require('./base122'), fs = require('fs'); let encodedData = base122.encode([0b01101100, 0b11110000]); fs.writeFileSync('encoded.txt', Buffer.from(encodedData), {encoding: 'utf-8'});
And to decode a base-122 encoded file:
let base122 = require('./base122'), fs = require('fs'); let fileData = fs.readFileSync('encoded.txt', {encoding: 'utf-8'}); let decodedData = base122.decode(fileData);
Using in Web Pages
Base-122 was created with the web in mind as an alternative to base-64 in data URIs. However, as explained in this article, base-122 is not recommended to be used in web pages. Base-64 compresses better than base-122 with gzip, and there is a performance penalty of decoding. However, the web decoder is still included in this repository as a proof-of-concept.
The script encodeFile.js is used as a convenience to re-encode base-64 data URIs from an HTML file into base-122. Suppose you have a base-64 encoded image in the file example.html as follows:
This can be re-encoded to base-122 using the following:
node encodeFile.js --html example.html example-base122.html
This produces the file example-base122.html
The file decode.min.js is a 469 byte decoder that can be included in web pages with base-122 encoded data. This can be copied into a base-122 encoded file, which will query the DOM for elements with the "data-b122" attribute. Passing the "--addDecoder" flag will automatically include it:
node encodeFile.js --html --add-decoder example.html example-base122.html
Will now produce the file with the decoder:
Development
If contributing changes to encoder/decoder functions, first run the tests with npm test. Note that there are two slightly different forms of the decoder function. base122.js contains a decoder function for the NodeJS implementation, while decode.js contains the decoder function with slight changes to run in the browser. Run npm run-script minify to minify decode.js into decode.min.js.