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- # deepmerge
-
- Merges the enumerable attributes of two or more objects deeply.
-
- > UMD bundle is 567B minified+gzipped
-
-
- ### Migration from 1.x to 2.0.0
-
- [***Check out the changes from version 1.x to 2.0.0***](https://github.com/KyleAMathews/deepmerge/blob/master/changelog.md#200)
-
- For the legacy array element-merging algorithm, see [the `arrayMerge` option below](#arraymerge).
-
-
- ### Webpack bug
-
- If you have `require('deepmerge')` (as opposed to `import merge from 'deepmerge'`) anywhere in your codebase, Webpack 3 and 4 have a bug that [breaks bundling](https://github.com/webpack/webpack/issues/6584).
-
- If you see `Error: merge is not a function`, add this alias to your Webpack config:
-
- ```
- alias: {
- deepmerge$: path.resolve(__dirname, 'node_modules/deepmerge/dist/umd.js'),
- }
- ```
-
-
- ## Getting Started
-
- ### Example Usage
- <!--js
- var merge = require('./')
- -->
-
- ```js
- var x = {
- foo: { bar: 3 },
- array: [{
- does: 'work',
- too: [ 1, 2, 3 ]
- }]
- }
-
- var y = {
- foo: { baz: 4 },
- quux: 5,
- array: [{
- does: 'work',
- too: [ 4, 5, 6 ]
- }, {
- really: 'yes'
- }]
- }
-
- var expected = {
- foo: {
- bar: 3,
- baz: 4
- },
- array: [{
- does: 'work',
- too: [ 1, 2, 3 ]
- }, {
- does: 'work',
- too: [ 4, 5, 6 ]
- }, {
- really: 'yes'
- }],
- quux: 5
- }
-
- merge(x, y) // => expected
- ```
-
-
- ### Installation
-
- With [npm](http://npmjs.org) do:
-
- ```sh
- npm install deepmerge
- ```
-
- deepmerge can be used directly in the browser without the use of package managers/bundlers as well: [UMD version from unpkg.com](https://unpkg.com/deepmerge/dist/umd.js).
-
-
- ### Includes
-
- CommonJS:
- ```
- var merge = require('deepmerge')
- ```
-
- ES Modules:
- ```
- import merge from 'deepmerge'
- ```
-
-
- # API
-
-
- ## `merge(x, y, [options])`
-
- Merge two objects `x` and `y` deeply, returning a new merged object with the
- elements from both `x` and `y`.
-
- If an element at the same key is present for both `x` and `y`, the value from
- `y` will appear in the result.
-
- Merging creates a new object, so that neither `x` or `y` is modified.
-
- **Note:** By default, arrays are merged by concatenating them.
-
- ## `merge.all(arrayOfObjects, [options])`
-
- Merges any number of objects into a single result object.
-
- ```js
- var x = { foo: { bar: 3 } }
- var y = { foo: { baz: 4 } }
- var z = { bar: 'yay!' }
-
- var expected = { foo: { bar: 3, baz: 4 }, bar: 'yay!' }
-
- merge.all([x, y, z]) // => expected
- ```
-
-
- ## Options
-
- ### `arrayMerge`
-
- There are multiple ways to merge two arrays, below are a few examples but you can also create your own custom function.
-
- #### Overwrite Array
-
- Overwrites the existing array values completely rather than concatenating them
-
- ```js
- const overwriteMerge = (destinationArray, sourceArray, options) => sourceArray
-
- merge(
- [1, 2, 3],
- [3, 2, 1],
- { arrayMerge: overwriteMerge }
- ) // => [3, 2, 1]
- ```
-
- #### Combine Array
-
- Combine arrays, such as overwriting existing defaults while also adding/keeping values that are different names
-
- To use the legacy (pre-version-2.0.0) array merging algorithm, use the following:
-
- ```js
- const emptyTarget = value => Array.isArray(value) ? [] : {}
- const clone = (value, options) => merge(emptyTarget(value), value, options)
-
- function combineMerge(target, source, options) {
- const destination = target.slice()
-
- source.forEach(function(e, i) {
- if (typeof destination[i] === 'undefined') {
- const cloneRequested = options.clone !== false
- const shouldClone = cloneRequested && options.isMergeableObject(e)
- destination[i] = shouldClone ? clone(e, options) : e
- } else if (options.isMergeableObject(e)) {
- destination[i] = merge(target[i], e, options)
- } else if (target.indexOf(e) === -1) {
- destination.push(e)
- }
- })
- return destination
- }
-
- merge(
- [{ a: true }],
- [{ b: true }, 'ah yup'],
- { arrayMerge: combineMerge }
- ) // => [{ a: true, b: true }, 'ah yup']
- ```
-
- ### `isMergeableObject`
-
- By default, deepmerge clones every property from almost every kind of object.
-
- You may not want this, if your objects are of special types, and you want to copy the whole object instead of just copying its properties.
-
- You can accomplish this by passing in a function for the `isMergeableObject` option.
-
- If you only want to clone properties of plain objects, and ignore all "special" kinds of instantiated objects, you probably want to drop in [`is-plain-object`](https://github.com/jonschlinkert/is-plain-object).
-
- ```js
- const isPlainObject = require('is-plain-object')
-
- function SuperSpecial() {
- this.special = 'oh yeah man totally'
- }
-
- const instantiatedSpecialObject = new SuperSpecial()
-
- const target = {
- someProperty: {
- cool: 'oh for sure'
- }
- }
-
- const source = {
- someProperty: instantiatedSpecialObject
- }
-
- const defaultOutput = merge(target, source)
-
- defaultOutput.someProperty.cool // => 'oh for sure'
- defaultOutput.someProperty.special // => 'oh yeah man totally'
- defaultOutput.someProperty instanceof SuperSpecial // => false
-
- const customMergeOutput = merge(target, source, {
- isMergeableObject: isPlainObject
- })
-
- customMergeOutput.someProperty.cool // => undefined
- customMergeOutput.someProperty.special // => 'oh yeah man totally'
- customMergeOutput.someProperty instanceof SuperSpecial // => true
- ```
-
-
- ### `clone`
-
- *Deprecated.*
-
- Defaults to `true`.
-
- If `clone` is `false` then child objects will be copied directly instead of being cloned. This was the default behavior before version 2.x.
-
-
- # Testing
-
- With [npm](http://npmjs.org) do:
-
- ```sh
- npm test
- ```
-
-
- # License
-
- MIT
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