invert

function Delta.invert(a: Delta, b: Delta): Delta

Returns the inverse of a delta against a base document. Applying the inverted delta undoes the original change.

Example

data-first

import { Delta } from "@monstermann/delta";

const base = Delta.insert([], "Hello");
const change = Delta.retain([], 5, { bold: true });

Delta.invert(change, base);
// [{ retain: 5, attributes: { bold: null } }]

const insert = pipe(
    [],
    Delta.retain(5),
    Delta.insert(" world")
);

Delta.invert(insert, base);
// [{ retain: 5 },
//  { delete: 6 }]

data-last

import { Delta } from "@monstermann/delta";

const base = Delta.insert([], "Hello");
const change = Delta.retain([], 5, { bold: true });

pipe(change, Delta.invert(base));
// [{ retain: 5, attributes: { bold: null } }]