Documentation / base / applyPatch

Function: applyPatch()

applyPatch(base, patch): DiffValue

Defined in: libs/base/src/diff.ts:331

Apply a DiffPatch to a given base value to produce a new value.

Behavior:

• set: sets/replaces the value at path (deep-cloned).
• del: deletes the value at path; deleting the root yields undefined.
• arr: applies array element sets first, then ins, then del (descending indices), minimizing index-shift side-effects during mutation.

Structural handling:

• Intermediate containers are created as needed: arrays for numeric next keys, objects otherwise.
• If an arr operation targets a non-array location, the array result is reconstructed by replaying the sub-ops against an empty array and then placed at the path.

Immutability:

• The function starts by deep-cloning base to avoid mutating the input.

Parameters

base

DiffValue

The source value onto which the patch is applied.

patch

DiffPatch

The patch to apply (produced by diff).

Returns

DiffValue

The result of applying patch to base.