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copying

copying is a library for making shallow copies. It requires you to make particular decisions about how you want properties to be copied from one object to another, to avoid ambiguity about what's actually happening in the copy.

This module exists to allow developers to make quick, deliberate decisions about how properties ought to be copied between objects, without compromising any clarity about what's actually going on.

Usage

This module's exports is a function that takes in a mandatory options object with the following properties, and returns a copier function.

  • enumerator: Must be one of the following string values:
    • "enumerable": The properties to copy will be iterated over using for .. in.
    • "ownKeys": The properties to copy will be retrieved using Reflect.ownKeys.
    • "keys": The properties to copy will be retrieved using Object.keys.
  • chain: Boolean. If true, the prototype chain will also be iterated over, and prototype properties will be copied to destination objects (not to the destination prototypes). If false, the prototype chain will not be used.
  • descriptor: Boolean. If true, properties will be copied by property descriptor. If false, properties will be copied by their resolved values.

Note: for .. in and Object.keys differ only in whether they include items in the prototype chain. Since we're deliberately choosing whether to iterate over the prototype chain, enumerable and keys are equivalent values for enumerator. Both are kept here, and implemented behind the scenes using the two different methods, in case there are performance differences between the two.

The returned copier function takes in objects similar to the way Object.assign works. The first argument is the destination object to be copied to, and the remaining arguments are source objects to be copied from, in the order they appear.

Examples

TODO (For now, take a look at the tests.)

License

MIT License. See LICENSE.txt