Endo API documentation - v0.2.0 / Exports / @endo/common / object-map

Module: object-map

Table of contents

Functions

• objectMap

Functions

objectMap

▸ objectMap<O, R>(original, mapFn): Record<keyof O, R>

By analogy with how Array.prototype.map will map the elements of an array to transformed elements of an array of the same shape, objectMap will do likewise for the string-named own enumerable properties of an object.

Typical usage applies objectMap to a CopyRecord, i.e., an object for which passStyleOf(original) === 'copyRecord'. For these, none of the following edge cases arise. The result will be a CopyRecord with exactly the same property names, whose values are the mapped form of the original's values.

When the original is not a CopyRecord, some edge cases to be aware of

• No matter how mutable the original object, the returned object is hardened.
• Only the string-named enumerable own properties of the original are mapped. All other properties are ignored.
• If any of the original properties were accessors, Object.entries will cause its getter to be called and will use the resulting value.
• No matter whether the original property was an accessor, writable, or configurable, all the properties of the returned object will be non-writable, non-configurable, data properties.
• No matter what the original object may have inherited from, and no matter whether it was a special kind of object such as an array, the returned object will always be a plain object inheriting directly from Object.prototype and whose state is only these new mapped own properties.

With these differences, even if the original object was not a CopyRecord, if all the mapped values are Passable, then the returned object will be a CopyRecord.

Type parameters

Name	Type	Description
O	extends Record<string, any>	-
R	R	map result

Parameters

Name	Type
original	O
mapFn	(value: O[keyof O], key: keyof O) => R

Returns

Record<keyof O, R>

Defined in

object-map.js:42