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pikapoo92 · web-flow · commit 246d66c335a8 · 2017-09-10T09:51:39.000-05:00
array.js homework complete
diff --git a/src/arrays.js b/src/arrays.js
@@ -1,50 +1,87 @@
-// Complete the following functions.
-// These functions only need to work with arrays.
-// Do NOT use the built in array methods to solve these. forEach, map, reduce, filter, includes, etc.
-// You CAN use concat, push, pop, etc. but do not use the exact method that you are replicating
-// You can use the functions that you have already written to help solve the other problems
-
-const each = (elements, cb) => {
-  // Iterates over a list of elements, yielding each in turn to the `cb` function.
-  // This only needs to work with arrays.
-  // based off http://underscorejs.org/#each
-};
-
-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 reduce = (elements, cb, memo = elements.shift()) => {
-  // Combine all elements into a single value going from left to right.
-  // Elements will be passed one by one into `cb`.
-  // `memo` is the starting value.  If `memo` is undefined then make `elements[0]` the initial value.
-};
-
-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.
-};
-
-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
-};
-
-/* 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];
-};
-
-/* eslint-enable no-unused-vars, max-len */
-
-module.exports = {
-  each,
-  map,
-  reduce,
-  find,
-  filter,
-  flatten
-};
+// Complete the following functions.
+// These functions only need to work with arrays.
+// Do NOT use the built in array methods to solve these. forEach, map, reduce, filter, includes, etc.
+// You CAN use concat, push, pop, etc. but do not use the exact method that you are replicating
+// You can use the functions that you have already written to help solve the other problems
+
+const each = (elements, cb) => {
+  // Iterates over a list of elements, yielding each in turn to the `cb` function.
+  // This only needs to work with arrays.
+  // 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 newArray = [];
+  for (let i = 0; i < elements.length; i++) {
+    newArray.push(cb(elements[i]));
+  }
+  return newArray;
+
+};
+
+const reduce = (elements, cb, memo = elements.shift()) => {
+  // Combine all elements into a single value going from left to right.
+  // Elements will be passed one by one into `cb`.
+  // `memo` is the starting value.  If `memo` is undefined then make `elements[0]` the initial value.
+  let reduced = memo;
+  for (let i = 0; i < elements.length; i++) {
+    result = cb(reduced, elements[i]);
+  }
+  return reduced;
+};
+
+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.
+  let truthy;
+  for (let i = 0; i < elements.length; i++) {
+    if (cb(elements[i])) {
+      truthy = elements[i];
+    }
+  }
+  return truthy;
+};
+
+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 truthyArr = [];
+  for (let i = 0; i < elements.length; i++) {
+    if (cb(elements[i])) {
+      truthyArr.push(elements[i]);
+    }
+  }
+  return truthyArr;
+};
+
+/* 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];
+  const result = [];
+  for(let i = 0; i < elements.length; i++) {
+      if(Array.isArray(elements[i])) {
+          result = result.concat(flatten(elements[i]));
+      } else {
+          result.push(elements[i]);
+      }
+  }
+  return result;
+};
+
+/* eslint-enable no-unused-vars, max-len */
+
+module.exports = {
+  each,
+  map,
+  reduce,
+  find,
+  filter,
+  flatten
+};
