mergeHandlerOptions

Merges the handler options of the file (baked) with the entry's (user). The result is a new object; neither input is changed.

The rules, in short (the entry is user):

• a plain object on both sides is merged key by key, recursively: security.csp from the entry keeps the file's security.headers;
• any other value replaces the file's: a primitive, false, null, an array, a function, a class instance (its reference is kept). An array is never concatenated: allowedHosts in the entry replaces the file's list;
• undefined means "not set": it does NOT erase a file value. A key that neither side sets is absent from the result;
• the keys __proto__, constructor and prototype are ignored at every depth;
• a merge may create at most 10 000 objects; more throws a RangeError (a cycle in the input).

Import#

import { mergeHandlerOptions } from "@shadow-js/dusk/server";

Signature#

function mergeHandlerOptions(
  baked: Partial<HandlerOptions>,
  user: Partial<HandlerOptions> | undefined,
): Partial<HandlerOptions>

Parameters#

Returns#

The merged options.

Throws#

• RangeError when the inputs are cyclic or nest beyond the object bound.

Examples#

const options = mergeHandlerOptions(
  { security: { allowedHosts: ["example.com"], headers: { frameOptions: "DENY" } } },
  { security: { csp: { directives: { "default-src": ["'self'"] } } } },
);
// security: { allowedHosts: ["example.com"], headers: { frameOptions: "DENY" }, csp: { ... } }