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sdgluck · Mar 27, 2017 · bc7e2f8 · bc7e2f8
2 parents e025d0b + a066030
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diff --git a/LICENSE b/LICENSE
@@ -0,0 +1,22 @@
+Copyright (c) 2017 Sam Gluck <sdgluck@gmail.com>
+
+MIT License
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/README.md b/README.md
@@ -4,7 +4,7 @@
 
 <p><h1 align="center">mewt</h1></p>
 
-<p align="center">:seedling: Immutability in under a kilobyte</p>
+<p align="center">Immutability in under one kilobyte</p>
 
 <p align="center">Made with ❤ at <a href="http://www.twitter.com/outlandish">@outlandish</a></p>
 
@@ -14,7 +14,11 @@
 
 <hr/>
 
-:cookie:  Under 1kb unminified. Zero dependencies.
+:seedling: Under 1kb (unminified), tiny API, zero dependencies.
+
+:+1: Makes all native array methods immutable operations.
+
+:v: Two simple methods `$set` and `$unset` for objects and arrays.
 
 :point_right: Built for Node ES2015 environments. Use a bundler, transpiler, and Proxy polyfill as required.
 
@@ -42,45 +46,72 @@ var immutable = require('mewt')
 
 ## Usage
 
-Create an immutable instance from a JavaScript array or object:
+Create an immutable instance from a JavaScript array or object.
+
+Both objects and arrays have the `$set` and `$unset` methods.
 
 ```js
-let immutableArray = immutable([])
-let immutableObect = immutable({})
+const immutableArray = immutable([])
+const immutableObect = immutable({})
+
+immutableArray[0] = 'Van Morrison' //=> Error "array is immutable"
+immutableObect.name = 'Van Morrison' //=> Error "object is immutable"
 ```
 
 ### Array
 
+Use `$set` and `$unset` to create new array with applied change.
+
+Use all array instance methods as usual, however those that would normally return a single 
+non-array value (pop, push, shift, unshift) will return an array containing the value and a new array
+(see part 2 in example below).
+
 ```js
 const arr = immutable([])
 
-// all array instance methods are available
+// 1. all array instance methods are available
 const arr1 = arr.concat('bubble')
 
-    console.log(arr) //=> ['bubble']
+    console.log(arr1) //=> ['bubble']
     console.log(arr1 === arr) //=> false
 
-// methods with non-array return value also return new 
-// array via destructuring (push, pop, shift, unshift)
+// 2. methods with non-array return value (push, pop, shift, unshift)
+// also return new array, accessible via destructuring
 const [val, arr2] = arr1.pop()
 
     console.log(val) //=> 'bubble'
     console.log(arr2) //=> []
     console.log(arr2 === arr1) //=> false
+
+// 3. use $set and $unset to get new array with changes
+const arr3 = arr2.$set(0, 'Iggy Pop')
+
+    console.log(arr3) //=> ['Iggy Pop']
+    console.log(arr3 === arr2) //=> false
 ```
 
 ### Object
 
+Use `$set` and `$unset` to create new object with applied change.
+
 ```js
 const obj = immutable({})
 
-// properties are added/updated using `$set`
-const obj1 = obj.set('album', 'Hunky Dory')
+// 1. properties are added/updated using `$set`
+const obj1 = obj.$set('album', 'Hunky Dory')
 
     console.log(obj1) //=> {album: 'Hunky Dory'}
+    console.log(obj1 === obj) //=> false
 
-// properties are deleted using `$unset`
+// 2. properties are deleted using `$unset`
 const obj2 = obj1.$unset('album')
 
     console.log(obj2) //=> {}
+    console.log(obj2 === obj1) //=> false
 ```
+
+## Contributing
+
+All pull requests and issues welcome!
+
+If you're not sure how, check out the [great video tutorials on egghead.io](http://bit.ly/2aVzthz)!
diff --git a/index.js b/index.js
@@ -1,22 +1,29 @@
-/** Create immutable instance of array or object.
- *  @returns {Array|Object} */
+/** @returns {Array|Object} */
 module.exports = function mewt (target) {
-  let current = target
-    , isArr = Array.isArray(target)
+  let isA = Array.isArray(target)
     , multiRet = 'push pop shift unshift'
-    , clone = v => isArr ? [].concat(v) : Object.assign({}, v)
+    , clone = (v, soft) => (v = isA ? [].concat(v) : Object.assign({}, v), soft ? v : mewt(v))
 
-  let override = fn => (...args) => {
-    let res = current[fn](...args)
-    current = clone(current)
-    return multiRet.includes(fn) ? [res, current] : current
+  let override = prop => (...args) => {
+    let res = target[prop](...args)
+    return multiRet.includes(prop) ? [res, clone(target)] : clone(res)
   }
 
-  if (!isArr && typeof target !== 'object')
+  let newObj, api = {
+    $set: (prop, val) => (newObj = clone(target, true), newObj[prop] = val, newObj),
+    $unset: prop => (newObj = clone(target, true), delete newObj[prop], newObj)
+  }
+
+  if (!isA && typeof target !== 'object')
     throw new Error('mewt accepts array or object')
 
   return new Proxy(target, {
-    set: (_, prop, val) => (current = clone(current), current[prop] = val, true),
-    get: (_, prop) => current[prop] && (current.hasOwnProperty(prop) ? current[prop] : override(prop))
+    set: () => {
+      throw new Error(`${isA ? 'array' : 'object'} is immutable`)
+    },
+    get: (_, prop) => {
+      if (api[prop]) return api[prop]
+      return target[prop] && (target.hasOwnProperty(prop) ? target[prop] : override(prop))
+    }
   })
 }
diff --git a/package.json b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "mewt",
   "version": "1.0.0",
-  "description": "Immutability in under a kilobyte",
+  "description": "Immutability in under one kilobyte",
   "main": "index.js",
   "scripts": {
     "test": "node test"

diff --git a/test.js b/test.js
@@ -20,6 +20,36 @@ test('array', (t) => {
     const n = mewt(a)
     t.notEqual(a, n)
   }
+  {
+    // throws on mutation
+    const a = mewt([])
+    t.throws(() => a[0] = 'Lodger', /immutable/)
+  }
+  {
+    // has $set & $unset
+    const a = mewt([])
+    t.equal(typeof a.$set, 'function')
+    t.equal(typeof a.$unset, 'function')
+  }
+  {
+    // get own property
+    const a = mewt([''])
+    t.equal(a[0], '')
+  }
+  {
+    // $set
+    const a = mewt([])
+    const n = a.$set(0, '')
+    t.deepEqual(n, [''])
+    t.notEqual(a, n)
+  }
+  {
+    // $unset
+    const a = mewt([''])
+    const n = a.$unset(0)
+    t.deepEqual(n, [])
+    t.notEqual(a, n)
+  }
   {
     // copyWithin
     const a = mewt([1, 2])
@@ -76,7 +106,7 @@ test('array', (t) => {
     // sort
     const a = mewt(['a', 'b', 'c'])
     const n = a.splice(0, 1)
-    t.deepEqual(n, ['b', 'c'])
+    t.deepEqual(n, ['a'])
     t.notEqual(a, n)
   }
   {
@@ -98,9 +128,36 @@ test('object', (t) => {
     t.notEqual(o, n)
   }
   {
-    //
-    const o = {}
-    const n = mewt(o)
+    // throws on mutation
+    const o = mewt({})
+    t.throws(() => o.track = 'The Promise', /immutable/)
+  }
+  {
+    // has $set & $unset
+    const o = mewt({})
+    t.equal(typeof o.$set, 'function')
+    t.equal(typeof o.$unset, 'function')
+  }
+  {
+    // get own property
+    const o = mewt({album: 'Aladdin Sane'})
+    t.equal(o.album, 'Aladdin Sane')
+  }
+  {
+    // $set
+    const o = mewt({})
+    const n = o.$set('album', 'Hours')
+    console.log(o.album)
+    t.equal(o.album, undefined)
+    t.equal(n.album, 'Hours')
+    t.notEqual(o, n)
+  }
+  {
+    // $unset
+    const o = mewt({album: 'Heroes'})
+    const n = o.$unset('album')
+    t.equal(o.album, 'Heroes')
+    t.equal(n.album, undefined)
     t.notEqual(o, n)
   }
   t.end()