Mar 21, 2018 · Mar 21, 2018 · Mar 21, 2018 · Mar 21, 2018
diff --git a/src/arrays.js b/src/arrays.js
  // 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 - 1; i++) {
    cb(elements[i], i);
  }
 };

 const map = (elements, cb) => {
  // Do NOT use .map, to complete this function.
  // Produces a new array of values by mapping each value in list through a transformation function (iteratee).
  // Return the new array.
  // Return the new array
  const arr = [];
  for (let i = 0; i < elements.length; i++) {
    arr.push(cb(elements[i]));
  }
  return arr;
 };

 const reduce = (elements, cb, startingValue) => {
  // Elements will be passed one by one into `cb` along with the `startingValue`.
  // `startingValue` should be the first argument passed to `cb` and the array element should be the second argument.
  // `startingValue` is the starting value.  If `startingValue` is undefined then make `elements[0]` the initial value.
  let returnValue = '';
  if (startingValue === undefined) {
    returnValue = elements[0];

    for (let i = 1; i < elements.length; i++) {
      returnValue = cb(returnValue, elements[i]);
    }
  } else if (startingValue !== undefined) {
    returnValue = startingValue;

    for (let i = 0; i < elements.length; i++) {
      returnValue = cb(returnValue, elements[i]);
    }
  }
  return returnValue;
 };


 const find = (elements, cb) => {
  // Do NOT use .includes, to complete this function.
  // 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++) {
    if (cb(elements[i]) === true) {
      return elements[i];
    }
  }
 };


 const filter = (elements, cb) => {
  // Do NOT use .filter, to complete this function.
  // 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
  for (let i = 0; i < elements.length; i++) {
    if (cb(elements[i]) === true) {
      return elements[i];
    }
  }
 };


 /* STRETCH PROBLEM */

 const flatten = (elements) => {
diff --git a/src/callbacks.js b/src/callbacks.js
 const firstItem = (arr, cb) => {
  // firstItem passes the first item of the given array to the callback function.
  cb(arr[0]);
 };

 const getLength = (arr, cb) => {
  // getLength passes the length of the array into the callback.
  cb(arr.length);
 };

 const last = (arr, cb) => {
  // last passes the last item of the array into the callback.
  cb(arr[arr.length - 1]);
 };

 const sumNums = (x, y, cb) => {
  // sumNums adds two numbers (x, y) and passes the result to the callback.
  cb(x + y);
 };

 const multiplyNums = (x, y, cb) => {
  // multiplyNums multiplies two numbers and passes the result to the callback.
  cb(x * y);
 };

 const contains = (item, list, cb) => {
  // contains checks if an item is present inside of the given array/list.
  // Pass true to the callback if it is, otherwise pass false.
  for (let i = 0; i < list.length; i++) {
    if (list[i] === item) {
      cb(true);
    } else {
      cb(false);
    }
  }
 };

 /* STRETCH PROBLEM */
  // removeDuplicates removes all duplicate values from the given array.
  // Pass the duplicate free array to the callback function.
  // Do not mutate the original array.


 };

 /* eslint-enable */
diff --git a/src/closure.js b/src/closure.js
  // 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 callCount = 0;
  return (...args) => {
    if (callCount === n) return null;
    callCount++;
    return cb(...args);
  };
 };

 /* STRETCH PROBLEM */
diff --git a/src/objects.js b/src/objects.js
  // 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.values(obj).map(key => obj[key]);
 };

 const mapObject = (obj, cb) => {
  // Like map for arrays, but for objects. Transform the value of each property in turn.
  // http://underscorejs.org/#mapObject
  return Object.values(obj).map(key => cb(obj[key]));
 };

 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]]);
 };

 /* STRETCH PROBLEMS */
Original file line number	Diff line number	Diff line change
Expand Up		@@ -14,12 +14,20 @@ 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 - 1; i++) {
		cb(elements[i], i);
		}
		};

		const map = (elements, cb) => {
		// Do NOT use .map, to complete this function.
		// Produces a new array of values by mapping each value in list through a transformation function (iteratee).
		// Return the new array.
		// Return the new array
		const arr = [];
		for (let i = 0; i < elements.length; i++) {
		arr.push(cb(elements[i]));
		}
		return arr;
		};

		const reduce = (elements, cb, startingValue) => {
Expand All		@@ -28,21 +36,49 @@ const reduce = (elements, cb, startingValue) => {
		// Elements will be passed one by one into `cb` along with the `startingValue`.
		// `startingValue` should be the first argument passed to `cb` and the array element should be the second argument.
		// `startingValue` is the starting value. If `startingValue` is undefined then make `elements[0]` the initial value.
		let returnValue = '';
		if (startingValue === undefined) {
		returnValue = elements[0];

		for (let i = 1; i < elements.length; i++) {
		returnValue = cb(returnValue, elements[i]);
		}
		} else if (startingValue !== undefined) {
		returnValue = startingValue;

		for (let i = 0; i < elements.length; i++) {
		returnValue = cb(returnValue, elements[i]);
		}
		}
		return returnValue;
		};


		const find = (elements, cb) => {
		// Do NOT use .includes, to complete this function.
		// 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++) {
		if (cb(elements[i]) === true) {
		return elements[i];
		}
		}
		};


		const filter = (elements, cb) => {
		// Do NOT use .filter, to complete this function.
		// 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
		for (let i = 0; i < elements.length; i++) {
		if (cb(elements[i]) === true) {
		return elements[i];
		}
		}
		};


		/* STRETCH PROBLEM */

		const flatten = (elements) => {
Expand Down
Original file line number	Diff line number	Diff line change
		@@ -1,26 +1,38 @@
		const firstItem = (arr, cb) => {
		// firstItem passes the first item of the given array to the callback function.
		cb(arr[0]);
		};

		const getLength = (arr, cb) => {
		// getLength passes the length of the array into the callback.
		cb(arr.length);
		};

		const last = (arr, cb) => {
		// last passes the last item of the array into the callback.
		cb(arr[arr.length - 1]);
		};

		const sumNums = (x, y, cb) => {
		// sumNums adds two numbers (x, y) and passes the result to the callback.
		cb(x + y);
		};

		const multiplyNums = (x, y, cb) => {
		// multiplyNums multiplies two numbers and passes the result to the callback.
		cb(x * y);
		};

		const contains = (item, list, cb) => {
		// contains checks if an item is present inside of the given array/list.
		// Pass true to the callback if it is, otherwise pass false.
		for (let i = 0; i < list.length; i++) {
		if (list[i] === item) {
		cb(true);
		} else {
		cb(false);
		}
		}
		};

		/* STRETCH PROBLEM */
Expand All		@@ -29,6 +41,8 @@ const removeDuplicates = (array, cb) => {
		// removeDuplicates removes all duplicate values from the given array.
		// Pass the duplicate free array to the callback function.
		// Do not mutate the original array.


		};

		/* eslint-enable */
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -5,17 +5,30 @@ 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 callCount = 0;
		return (...args) => {
		if (callCount === n) return null;
		callCount++;
		return cb(...args);
		};
Copy link indifferentghostMar 21, 2018 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. This is exactly the solution code from the solution branch... In the future I'd like to see where you got with your own code.
		};

		/* STRETCH PROBLEM */
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -5,22 +5,26 @@ 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.values(obj).map(key => obj[key]);
Copy link indifferentghostMar 21, 2018 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. `Object.values(obj);` is sufficient the code you currently have actually breaks.
		};

		const mapObject = (obj, cb) => {
		// Like map for arrays, but for objects. Transform the value of each property in turn.
		// http://underscorejs.org/#mapObject
		return Object.values(obj).map(key => cb(obj[key]));
Copy link indifferentghostMar 21, 2018 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. There's a few things wrong with this. I assume you wanted to use`Object.keys(obj)` if you wanted to access the values, but this should also be building a new object with the same keys, and values that are passed into the callback function (`cb`). At the moment you're returning an array of`NaN` objects (because of the particular callback function).
		};

		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]]);
		};

		/* STRETCH PROBLEMS */
Expand Down