defu
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    5.0.0 • Public • Published

    defu

    🌊 defu

    Assign default properties, recursively. Lightweight and Fast!

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    Install

    Install package:

    yarn add defu
    # or
    npm install defu

    Usage

    const options = defu (object, ...defaults)

    Leftmost arguments have more priority when assigning defaults.

    Arguments

    • object (Object): The destination object.
    • source (Object): The source object.
    const defu = require('defu')
    
    console.log(defu({ 'a': { 'b': 2 } }, { 'a': { 'b': 1, 'c': 3 } }))
    // => { a: { b: 2, c: 3 } }

    Custom Merger

    Sometimes default merging strategy is not desirable. Using defu.extend we can create a custom instance with different merging strategy.

    This function accepts obj (source object), key and value (current value) and should return true if applied custom merging.

    Example: Sum numbers instead of overriding

    const ext = defu.extend((obj, key, value) => {
      if (typeof obj[key] === 'number' && typeof value === 'number') {
        obj[key] += val
        return true
      }
    })
    
    ext({ cost: 15 }, { cost: 10 }) // { cost: 25 }

    Function Merger

    Using defu.fn, if user provided a function, it will be called with default value instead of merging.

    I can be useful for default values manipulation.

    Example: Filter some items from defaults (array) and add 20 to the count default value.

    defu.fn({
      ignore: (val) => val.filter(item => item !== 'dist'),
      count: (count) => count + 20
     }, {
       ignore: ['node_modules','dist'],
       count: 10
     })
     /*
     {
        ignore: ['node_modules'],
        count: 30
      }
      */

    Note: if the default value is not defined, the function defined won't be called and kept as value.

    Array Function Merger

    defu.arrayFn is similar to defu.fn but only applies to array values defined in defaults.

    Example: Filter some items from defaults (array) and add 20 to the count default value.

    defu.arrayFn({
      ignore(val) => val.filter(i => i !== 'dist'),
      count: () => 20
     }, {
       ignore: [
         'node_modules',
         'dist'
       ],
       count: 10
     })
     /*
      {
        ignore: ['node_modules'],
        count: () => 20
      }
      */

    Note: the function is called only if the value defined in defaults is an aray.

    Remarks

    • object and defaults are not modified
    • Nullish values (null and undefined) are skipped. Please use defaults-deep or omit-deep or lodash.defaultsdeep if you need to preserve or different behavior.
    • Assignment of __proto__ and constructor keys will be skipped to prevent security issues with object pollution.
    • Will concat array values (if default property is defined)
    console.log(defu({ array: ['b', 'c'] }, { array: ['a'] }))
    // => { array: ['a', 'b', 'c']}

    License

    MIT. Made with 💖

    Keywords

    none

    Install

    npm i defu

    DownloadsWeekly Downloads

    1,537,349

    Version

    5.0.0

    License

    MIT

    Unpacked Size

    15.9 kB

    Total Files

    7

    Last publish

    Collaborators

    • pi0