text-operation

Classes for Rich Text Operations using Operational Transformation

• Overview
• Installing
• Usage
• Contributing
• Licence

Overview

This package is heavily based on firepad's OT operations, which were in turn based on ot.js. Yay OSS!

This package is a conversion of their masterful work into Typescript + ES6, and turned into an easy to use module.

Installation

npm i -S text-operation

Usage

The easiest way to get familiar with the TextOperation class is to check out text-operation.utils.spec.js

The OT operations we allow are retain insert delete. A single TextOperation will contain one or many of these operations, but must traverse exactly entire string for which they will be applied:

import { TextOperation } from 'text-operation';

const testString = 'I am a test string';

const o = new TextOperation();
o.retain(2);
o.delete(2);
o.insert('was');
o.retain(14);
o.insert('!');

// apply operations to a string
console.log(o.apply(testString)); // I was a test string!

// composition example
const o2 = new TextOperation();
o2.retain(2);
o2.delete(3);
o2.insert('still am');
o2.retain(15);
o2.insert('!!');

const composed = o.compose(o2);
console.log(composed);
// TextOperation {
//   ops:
//    [ TextOp { type: 'retain', chars: 2, text: null, attributes: {} },
//      TextOp { type: 'insert', chars: null, text: 'still am', attributes: {} },
//      TextOp { type: 'delete', chars: 2, text: null, attributes: null },
//      TextOp { type: 'retain', chars: 14, text: null, attributes: {} },
//      TextOp { type: 'insert', chars: null, text: '!!!!', attributes: {} } ],
//   baseLength: 18,
//   targetLength: 28 }

console.log(composed.apply(testString)); // I still am a test string!!!

// transformation example
const simpleString = 'abcdef';

const op1 = new TextOperation();
const op2 = new TextOperation();

op1.retain(6).insert('ghijk');
op2.retain(3).delete(3);
const transformed = op1.transform(op2);
console.log(transformed[0].toJSON(), transformed[1].toJSON()); // [ 3, 'ghijk' ] [ 3, -3, 5 ]

console.log(transformed[1].apply(op1.apply(simpleString))); // abcghijk

Contributing

This project welcomes code contributions, bug reports and feature requests. Please see the guidelines in CONTRIBUTING.md if you are interested in contributing.