JAVASCRIPT

quill js server side delta

const Delta = require('quill-delta');	// npm install quill-delta

let serverSideDelta = {};

let deltaToAdd = <some client side delta>;

// Apply clientSideDelta on serverSideDelta
serverSideDelta = {
  ops: new Delta(serverSideDelta.ops).compose(new Delta(deltaToAdd))).ops
};