unpartial

Unpartial a type.

It is very common to define a config type and Partial<> it in a function argument. When we received the argument, we want to merge it with our default config before using it:

import { unpartial } from 'unpartial'

interface Config {
  require: { a: number }
  optional?: { a: number }
}
const defaultConfig: Config = { require: { a: 1 } }

function foo(givenConfig?: Partial) {
  const config = unpartial(defaultConfig, givenConfig);
  // use config with type safety
}

Code completion is available as you type:

const config = unpartial(defaultConfig, { /* code completion here */});

It also supports merging two default configs. This is useful when you are extending the interface from another package/class.

import { unpartial } from 'unpartial'

import { Option, defaultOption } from 'another-package'

interface MyOption extends Option { ... }

const myDefaultOption = { ... }

function foo(givenOption?: Partial) {
  const option = unpartial(defaultOption, myDefaultOption, givenOption)
}

This is deprecated because currently TypeScript does not support optional generic type, so it is not possible to create a satisfactory signature that works with both implicit and explicit type.

Instead, please use composition when combining 3 or more values:

unpartial(unpartial(defaultOption, myDefaultOption), givenOption)

There are 3 more functions available in this library:

• unpartialRecursively(): unpartial() deeply.
  In practice, this does not seem to be useful. Maybe will be deprecated and removed in the future.
• required(): an alternative version of unpartial() with a different type management.
  This will become identical to unpartial() in the future.
• requiredDeep(): an alternative version of unpartialRecursively() with a different type management.
  This will become identical to unpartial() in the future.

unpartial is also exposed through type-plus. It contains many more functions and type utilities.

Feel free to check it out.

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