Higher orders hw

06week/higherOrder/higherOrder.js

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+'use strict';
+
+
+function forEach(arr, callback) {
+  for (let i = 0; i < arr.length; i++){
+    callback(arr)
+  }
+}
+
+
+function map(arr, callback) {
+  let newArray = []
+  for (let i = 0; i < arr.length; i++){
+    let newNum = callback(arr[i])
+    newArray.push(newNum)
+
+  }
+  return newArray;
+}
+
+function filter(arr, callback) {
+  let newArray = []
+  for (let i = 0; i < arr.length; i++){
+    if(callback(arr[i]) == true){
+      newArray.push(arr[i])
+    };
+  }
+  return newArray
+}
+
+function some(arr, callback) {
+  for (let i = 0; i < arr.length; i++){
+    if(callback(arr[i]) == true){
+      return true
+    }
+  }
+  return false
+}
+
+function every(arr, callback) {
+  for (let i = 0; i < arr.length; i++){
+    if(callback(arr[i]) == false){
+      return false;
+    }
+  }
+  return true
+}
+
+module.exports = {
+  forEach,
+  map,
+  filter,
+  some,
+  every
+}

06week/higherOrder/package.json

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+{
+  "scripts": {
+    "start": "node higherOrder",
+    "test": "mocha"
+  },
+  "devDependencies": {
+    "mocha": "^5.2.0"
+  }
+}

06week/higherOrder/test.js

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+'use strict';
+
+const assert = require('assert');
+const forEach = require("./higherOrder").forEach;
+const map = require("./higherOrder").map;
+const filter = require("./higherOrder").filter;
+const some = require("./higherOrder").some;
+const every = require("./higherOrder").every;
+
+if (typeof describe === 'function') {
+
+    describe('#forEach()', () => {
+      it('should call the callback the array.length number of times', () => {
+        let count = 0;
+        forEach([1, 2, 3], () => {
+          count++;
+        });
+        assert.equal(count, 3);
+      });
+    });
+
+    describe('#map()', () => {
+      const arr = [1, 2, 3];
+      const mapped = map(arr, (num) => {
+        return num * num;
+      });
+      it('should return new array with mapped items', () => {
+        assert.deepEqual(mapped, [1, 4, 9]);
+      });
+      it('should not affect the original array', () => {
+        assert.deepEqual(arr, [1, 2, 3]);
+      })
+    });
+
+    describe('#filter()', () => {
+      it('should return an array of items that pass the predicate test', () => {
+        const filtered = filter([1, 2, 3], (num) => {
+          return num % 2 === 0;
+        });
+        assert.deepEqual(filtered, [2]);
+      });
+    });
+
+    describe('#some()', () => {
+      let count = 0;
+      const somed = some([1, 2, 3, 4], (num) => {
+        count++;
+        return num % 2 === 0;
+      });
+      it('should return true if at least one item passes the predicate test', () => {
+        assert.equal(somed, true);
+      });
+      it('should stop at the first item that passes the predicate test', () => {
+        assert.equal(count, 2);
+      });
+      it('should return false if no items pass the predicate test', () => {
+        const somed = some([1, 3, 5], (num) => {
+          return num % 2 === 0;
+        });
+        assert.equal(somed, false);
+      });
+    });
+
+    describe('#every()', () => {
+      it('should return true if at all passes the predicate test', () => {
+        const everied = every([2, 4, 6], (num) => {
+          return num % 2 === 0;
+        });
+        assert.equal(everied, true);
+      });
+      let count = 0;
+      const everied = every([2, 3, 4, 5], (num) => {
+        count++;
+        return num % 2 === 0;
+      });
+      it('should return false if any item fails the predicate test', () => {
+        assert.equal(everied, false);
+      });
+      it('should stop at the first item that fails the predicate test', () => {
+        assert.equal(count, 2);
+      });
+    });
+
+  } else {
+
+    console.log('Only run the tests on this one!')
+
+  }