Added Solutions

vibe · vibe · commit 3880abb618c4 · 2017-10-03T16:44:23.000-07:00
diff --git a/package-lock.json b/package-lock.json
diff --git a/src/arrays.js b/src/arrays.js
@@ -9,35 +9,85 @@ const each = (elements, cb) => {
   // This only needs to work with arrays.
   // You should also pass the index into `cb` as the second argument
   // based off http://underscorejs.org/#each
+
+  for (let i = 0; i < elements.length; i++) {
+    cb(elements[i], i);
+  }
 };
 
 const map = (elements, cb) => {
   // Produces a new array of values by mapping each value in list through a transformation function (iteratee).
   // Return the new array.
+  const mapped = [];
+
+  each(elements, (element, index) => {
+    mapped.push(cb(element, index));
+  });
+
+  return mapped;
 };
 
 const reduce = (elements, cb, startingValue) => {
   // Combine all elements into a single value going from left to right.
   // Elements will be passed one by one into `cb`.
   // `startingValue` is the starting value.  If `startingValue` is undefined then make `elements[0]` the initial value.
+
+  let accumulator = startingValue === undefined ? elements[0] : startingValue;
+  elements = startingValue === undefined ? elements.slice(1) : elements;
+
+  each(elements, (element, index) => {
+    accumulator = cb(accumulator, element, index);
+  });
+
+  return accumulator;
 };
 
 const find = (elements, cb) => {
   // Look through each value in `elements` and pass each element to `cb`.
   // If `cb` returns `true` then return that element.
   // Return `undefined` if no elements pass the truth test.
+  for (let i = 0; i < elements.length; i++) {
+    const response = cb(elements[i]);
+    if (response) {
+      return elements[i];
+    }
+  }
+  return undefined;
 };
 
 const filter = (elements, cb) => {
   // Similar to `find` but you will return an array of all elements that passed the truth test
   // Return an empty array if no elements pass the truth test
+  const filtered = [];
+  each(elements, (element, index) => {
+    const response = cb(element);
+    if (response) {
+      filtered.push(element);
+    }
+  });
+
+  return filtered;
 };
 
 /* Extra Credit */
 
 const flatten = (elements) => {
   // Flattens a nested array (the nesting can be to any depth).
   // Example: flatten([1, [2], [3, [[4]]]]); => [1, 2, 3, 4];
+
+  let elementsLeft = [...elements];
+  let flatElements = [];
+
+  while (elementsLeft.length) {
+    const item = elementsLeft[0];
+    elementsLeft = elementsLeft.slice(1);
+    if (Array.isArray(item)) {
+      elementsLeft = [...elementsLeft, ...item];
+    } else {
+      flatElements = [...flatElements, item];
+    }
+  }
+  return flatElements;
 };
 
 /* eslint-enable no-unused-vars, max-len */
diff --git a/src/callbacks.js b/src/callbacks.js
@@ -23,36 +23,61 @@
 // Write a function called firstItem that passes the first item of the given array to the callback function
 // code here
 
+
+const firstItem = (foods, cb) => {
+  cb(foods[0]);
+};
+
+
+
 const foods = ['pineapple', 'mango', 'ribeye', 'curry', 'tacos', 'ribeye', 'mango'];
 
+console.log(foods);
+
 firstItem(foods, (firstItem) => {
   console.log(`The first item is ${firstItem}.`);
 });
 
 // Write a function called getLength that passes the length of the array into the callback
 // code here
 
+const getLength = (foods, cb) => {
+  cb(foods.length)
+}
+
 getLength(foods, (length) => {
   console.log(`The length of the array is ${length}.`);
 });
 
 // Write a function called last which passes the last item of the array into the callback
 // code here
 
+const last = (foods, cb) => {
+  cb(foods[foods.length - 1])
+}
+
 last(foods, (lastItem) => {
   console.log(`The last item in the array is ${lastItem}.`);
 });
 
 // Write a function called sumNums that adds two numbers and passes the result to the callback
 // code here
 
+const sumNums = (x, y, cb) => {
+  cb(x+y);
+}
+
 sumNums(5, 10, (sum) => {
   console.log(`The sum is ${sum}.`);
 });
 
 // Write a function called multiplyNums that multiplies two numbers and passes the result to the callback
 // code here
 
+const multiplyNums = (x, y, cb) => {
+  cb(x*y)
+}
+
 multiplyNums(5, 10, (product) => {
   console.log(`The product is ${product}.`);
 });
@@ -61,6 +86,10 @@ multiplyNums(5, 10, (product) => {
 // Pass true to the callback if it is, otherwise pass false
 // code here
 
+const contains = (haystack, needle, cb) => {
+  return cb(haystack.indexOf(needle) >= 0);
+}
+
 contains(foods, 'ribeye', (result) => {
   console.log(result ? 'ribeye is in the array' : 'ribeye is not in the array');
 });
@@ -69,13 +98,30 @@ contains(foods, 'ribeye', (result) => {
 // Pass the array to the callback function.  Do not mutate the original array.
 // code here
 
+const removeDuplicates = (foods, cb) => {
+  const noDupes = [];
+   for(let i = 0; i < foods.length; i++) {
+     if(noDupes.indexOf(foods[i]) < 0) {
+       noDupes.push(foods[i])
+     }
+   }
+   cb(noDupes);
+}
+
+
 removeDuplicates(foods, (uniqueFoods) => {
   console.log(`foods with duplicates removed: ${uniqueFoods}`);
 });
 
 // Write a function called forEach that iterates over the provided array and passes the value and index into the callback.
 // code here
 
+const forEach = (foods, cb) => {
+  for(let i = 0; i < foods.length; i++) {
+    cb(foods[i], i)
+  }
+}
+
 forEach(foods, (value, index) => {
   console.log(`${value} is at index ${index}.`);
 });
diff --git a/src/closure.js b/src/closure.js
@@ -5,17 +5,37 @@ const counter = () => {
   // Example: const newCounter = counter();
   // newCounter(); // 1
   // newCounter(); // 2
+  let count = 0;
+
+  return () => ++count;
 };
 
 const counterFactory = () => {
   // Return an object that has two methods called `increment` and `decrement`.
   // `increment` should increment a counter variable in closure scope and return it.
   // `decrement` should decrement the counter variable and return it.
+  let count = 0;
+
+  return {
+    increment: () => ++count,
+    decrement: () => --count,
+  };
 };
 
 const limitFunctionCallCount = (cb, n) => {
   // Should return a function that invokes `cb`.
   // The returned function should only allow `cb` to be invoked `n` times.
+  let invoked = 0;
+  //  error  Arrow function used ambiguously with a conditional expression ?!?
+  //  return (...args) => ++invoked <= n ? cb(...args) : null;
+  return (...args) => {
+    invoked += 1;
+
+    if (invoked <= n) {
+      return cb(...args);
+    }
+    return null;
+  };
 };
 
 /* Extra Credit */
@@ -27,6 +47,16 @@ const cacheFunction = (cb) => {
   // If the returned function is invoked with arguments that it has already seen
   // then it should return the cached result and not invoke `cb` again.
   // `cb` should only ever be invoked once for a given set of arguments.
+  const cache = {
+  };
+
+  return (...args) => {
+    const cacheKey = args.toString();
+    if (!(cacheKey in cache)) {
+      cache[cacheKey] = cb(...args);
+    }
+    return cache[cacheKey];
+  };
 };
 
 /* eslint-enable no-unused-vars */
diff --git a/src/objects.js b/src/objects.js
@@ -5,22 +5,31 @@ const keys = (obj) => {
   // Retrieve all the names of the object's properties.
   // Return the keys as strings in an array.
   // Based on http://underscorejs.org/#keys
+  return Object.keys(obj);
 };
 
 const values = (obj) => {
   // Return all of the values of the object's own properties.
   // Ignore functions
   // http://underscorejs.org/#values
+  return Object.keys(obj).filter(key => !(typeof obj[key] === 'function')).map(key => obj[key]);
 };
 
-const mapObject = (obj, cb) => {
+const mapObject = (obj, cb, onlyValues = true) => {
   // Like map for arrays, but for objects. Transform the value of each property in turn.
   // http://underscorejs.org/#mapObject
+  // Added an onlyValues param, that you can set to false, if you want to execute callback on said function.
+
+  return Object.keys(obj).reduce((transformedObj, key) => {
+    transformedObj[key] = (onlyValues && obj[key] === 'function') ? obj[key] : cb(obj[key]);
+    return transformedObj;
+  }, {});
 };
 
 const pairs = (obj) => {
   // Convert an object into a list of [key, value] pairs.
   // http://underscorejs.org/#pairs
+  return Object.keys(obj).map(key => [key, obj[key]]);
 };
 
 /* Extra credit */
@@ -29,12 +38,23 @@ const invert = (obj) => {
   // Returns a copy of the object where the keys have become the values and the values the keys.
   // Assume that all of the object's values will be unique and string serializable.
   // http://underscorejs.org/#invert
+  return Object.keys(obj).reduce((transformedObj, key) => {
+    const value = obj[key];
+    transformedObj[value] = key;
+    return transformedObj;
+  }, {});
 };
 
 const defaults = (obj, defaultProps) => {
   // Fill in undefined properties that match properties on the `defaultProps` parameter object.
   // Return `obj`.
   // http://underscorejs.org/#defaults
+  // return { ...defaultProps, ...obj };
+
+  return Object.keys(defaultProps).reduce((transformedObj, key) => {
+    transformedObj[key] = key in obj ? obj[key] : defaultProps[key];
+    return transformedObj;
+  }, obj);
 };
 
 /* eslint-enable no-unused-vars */
