JS armstrong numbers

javascript/armstrong-numbers/.exercism/metadata.json

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+{"track":"javascript","exercise":"armstrong-numbers","id":"a0217a4d961c48c2beba064ccea0386d","url":"https://exercism.io/my/solutions/a0217a4d961c48c2beba064ccea0386d","handle":"rolandleth","is_requester":true,"auto_approve":false}

javascript/armstrong-numbers/README.md

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+# Armstrong Numbers
+
+An [Armstrong number](https://en.wikipedia.org/wiki/Narcissistic_number) is a number that is the sum of its own digits each raised to the power of the number of digits.
+
+For example:
+
+- 9 is an Armstrong number, because `9 = 9^1 = 9`
+- 10 is *not* an Armstrong number, because `10 != 1^2 + 0^2 = 1`
+- 153 is an Armstrong number, because: `153 = 1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153`
+- 154 is *not* an Armstrong number, because: `154 != 1^3 + 5^3 + 4^3 = 1 + 125 + 64 = 190`
+
+Write some code to determine whether a number is an Armstrong number.
+
+## Setup
+
+Go through the setup instructions for Javascript to
+install the necessary dependencies:
+
+[https://exercism.io/tracks/javascript/installation](https://exercism.io/tracks/javascript/installation)
+
+## Requirements
+
+Install assignment dependencies:
+
+```bash
+$ npm install
+```
+
+## Making the test suite pass
+
+Execute the tests with:
+
+```bash
+$ npm test
+```
+
+In the test suites all tests but the first have been skipped.
+
+Once you get a test passing, you can enable the next one by
+changing `xtest` to `test`.
+
+
+## Source
+
+Wikipedia [https://en.wikipedia.org/wiki/Narcissistic_number](https://en.wikipedia.org/wiki/Narcissistic_number)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

javascript/armstrong-numbers/armstrong-numbers.js

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+export const validate = (number) => {
+	if (number < 10) {
+		return true
+	}
+
+	if (number < 100) {
+		return false
+	}
+
+	const n = `${number}`
+	const result = n.split("").reduce((prev, current) => {
+		const value = parseInt(current, 10)
+
+		return prev + value ** n.length
+	}, 0)
+
+	return result == number
+}

javascript/armstrong-numbers/armstrong-numbers.spec.js

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+import { validate } from "./armstrong-numbers"
+
+describe("ArmstrongNumber", () => {
+	test("Single digit numbers are Armstrong numbers", () => {
+		const input = 5
+		expect(validate(input)).toBe(true)
+	})
+
+	test("There are no 2 digit Armstrong numbers", () => {
+		const input = 10
+		expect(validate(input)).toBe(false)
+	})
+
+	test("Three digit number that is an Armstrong number", () => {
+		const input = 153
+		expect(validate(input)).toBe(true)
+	})
+
+	test("Three digit number that is not an Armstrong number", () => {
+		const input = 100
+		expect(validate(input)).toBe(false)
+	})
+
+	test("Four digit number that is an Armstrong number", () => {
+		const input = 9474
+		expect(validate(input)).toBe(true)
+	})
+
+	test("Four digit number that is not an Armstrong number", () => {
+		const input = 9475
+		expect(validate(input)).toBe(false)
+	})
+
+	test("Seven digit number that is an Armstrong number", () => {
+		const input = 9926315
+		expect(validate(input)).toBe(true)
+	})
+
+	test("Seven digit number that is not an Armstrong number", () => {
+		const input = 9926314
+		expect(validate(input)).toBe(false)
+	})
+})

javascript/armstrong-numbers/package.json

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+{
+  "name": "exercism-javascript",
+  "version": "0.0.0",
+  "description": "Exercism exercises in Javascript.",
+  "author": "Katrina Owen",
+  "private": true,
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/exercism/javascript"
+  },
+  "devDependencies": {
+    "babel-eslint": "^10.0.1",
+    "babel-jest": "^23.6.0",
+    "babel-plugin-transform-builtin-extend": "^1.1.2",
+    "babel-preset-env": "^1.7.0",
+    "eslint": "^5.12.1",
+    "eslint-config-airbnb-base": "^13.1.0",
+    "eslint-plugin-import": "^2.15.0",
+    "jest": "^23.6.0"
+  },
+  "jest": {
+    "modulePathIgnorePatterns": [
+      "package.json"
+    ]
+  },
+  "babel": {
+    "presets": [
+      [
+        "env",
+        {
+          "targets": [
+            {
+              "node": "current"
+            }
+          ]
+        }
+      ]
+    ],
+    "plugins": [
+      [
+        "babel-plugin-transform-builtin-extend",
+        {
+          "globals": [
+            "Error"
+          ]
+        }
+      ],
+      [
+        "transform-regenerator"
+      ]
+    ]
+  },
+  "scripts": {
+    "test": "jest --no-cache ./*",
+    "watch": "jest --no-cache --watch ./*",
+    "lint": "eslint .",
+    "lint-test": "eslint . && jest --no-cache ./* "
+  },
+  "eslintConfig": {
+    "parser": "babel-eslint",
+    "parserOptions": {
+      "ecmaVersion": 7,
+      "sourceType": "module"
+    },
+    "env": {
+      "es6": true,
+      "node": true,
+      "jest": true
+    },
+    "extends": "airbnb-base",
+    "rules": {
+      "import/no-unresolved": "off",
+      "import/extensions": "off",
+      "import/prefer-default-export": "off",
+      "import/no-default-export": "off"
+    }
+  },
+  "license": "MIT",
+  "dependencies": {}
+}