JS proxy

Author: shama

javascript-proxy/README.md

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+# JavaScript Proxy
+
+> [https://youtu.be/gZ4MCb2nlfQ](https://youtu.be/gZ4MCb2nlfQ)
+
+Install [Node.js](https://nodejs.org/).
+
+Within this folder run the terminal command `npm install` to install the
+`dependencies` and `devDependencies`.
+
+Then run `npm start` to run the app viewable on `http://localhost:9966`.

javascript-proxy/array.js

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+
+const IndexedArray = new Proxy(Array, {
+  construct: function (target, [originalArray]) {
+    const index = {}
+    originalArray.forEach(function (item) {
+      index[item.id] = item
+    })
+
+    const newArray = new target(...originalArray)
+
+    return new Proxy(newArray, {
+      get: function (target, name) {
+        if (name === 'push') {
+          return function (item) {
+            index[item.id] = item
+            return target[name].call(target, item)
+          }
+        } else if (name === 'findById') {
+          return function (searchId) {
+            return index[searchId]
+          }
+        }
+        return target[name]
+      }
+    })
+  }
+})
+
+const bears = new IndexedArray([
+  {
+    id: 2,
+    name: 'grizzly',
+  },
+  {
+    id: 4,
+    name: 'black',
+  },
+  {
+    id: 3,
+    name: 'polar',
+  },
+])
+
+bears.push({
+  id: 55,
+  name: 'brown'
+})
+
+const brown = bears.findById(55)
+console.log(brown)
+console.log(bears.findById(3))
+
+// const index = {}
+// bears.forEach(function (bear) {
+//   index[bear.id] = bear
+// })
+//
+// const polar = index[3]
+// const black = index[4]

javascript-proxy/index.js

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+let bears = { grizzly: true }
+
+let grizzlyCount = 0
+
+const proxyBears = new Proxy(bears, {
+  get: function (target, prop) {
+    if (prop === 'grizzly') grizzlyCount++
+    return target[prop]
+  },
+  set: function (target, prop, value) {
+    if (['grizzly', 'brown', 'polar'].indexOf(prop) === -1) {
+      throw new Error('THAT IS TOTALLY NOT A BEAR!')
+    }
+    target[prop] = value
+  },
+  deleteProperty: function (target, prop) {
+    console.log(`You have deleted ${prop}`)
+    delete target[prop]
+  }
+})
+
+//proxyBears.aardvark = true
+proxyBears.polar = true
+//delete proxyBears.polar
+//console.log(proxyBears.polar)
+
+// proxyBears.grizzly
+// proxyBears.grizzly
+// proxyBears.grizzly
+// proxyBears.grizzly
+// console.log(grizzlyCount)
+
+function growl() {
+  return 'grrr'
+}
+const loudGrowl = new Proxy(growl, {
+  apply: function (target, thisArg, args) {
+    return target().toUpperCase() + '!!!'
+  }
+})
+
+console.log(loudGrowl())
+
+
+
+
+
+
+
+
+
+
+

javascript-proxy/package.json

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+{
+  "name": "javascript-proxy",
+  "version": "0.1.0",
+  "description": "",
+  "main": "index.js",
+  "dependencies": {},
+  "devDependencies": {
+    "budo": "^9.1.0"
+  },
+  "scripts": {
+    "start": "budo array.js --live",
+    "test": "node test.js"
+  },
+  "author": "Kyle Robinson Young <[email protected]> (http://dontkry.com)",
+  "license": "MIT"
+}

javascript-proxy/person.js

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+const person = {
+  first: 'Bear',
+  last: 'McBearison'
+}
+
+const cleverPerson = new Proxy(person, {
+  get: function (target, prop) {
+    if (!(prop in target)) {
+      return prop.split('_').map(function (part) {
+        return target[part]
+      }).join(' ')
+    }
+    return target[prop]
+  }
+})
+
+console.log(cleverPerson.last_first_first_first_first_first)
+
+cleverPerson.last = 'Beary'
+console.log(cleverPerson.first_last)