Complete stretch exercises for Sprint 2

Author: Richiealx

Sprint-2/stretch/count-words.js

@@ -1,28 +1,26 @@
-/*
-  Count the number of times a word appears in a given string.
+function countWords(text) {
+  if (typeof text !== "string") {
+    throw new Error("Input must be a string");
+  }
 
-  Write a function called countWords that
-    - takes a string as an argument
-    - returns an object where
-          - the keys are the words from the string and
-          - the values are the number of times the word appears in the string
+  // remove punctuation and make lowercase
+  const cleanedText = text.toLowerCase().replace(/[.,!?]/g, "");
 
-  Example
-  If we call countWords like this:
+  const words = cleanedText.split(/\s+/);
 
-  countWords("you and me and you") then the target output is { you: 2, and: 2, me: 1 }
+  const counts = {};
 
-  To complete this exercise you should understand
-    - Strings and string manipulation
-    - Loops
-    - Comparison inside if statements
-    - Setting values on an object
+  for (const word of words) {
+    if (!word) continue;
 
-## Advanced challenges
+    if (counts[word]) {
+      counts[word]++;
+    } else {
+      counts[word] = 1;
+    }
+  }
 
-1. Remove all of the punctuation (e.g. ".", ",", "!", "?") to tidy up the results
+  return counts;
+}
 
-2. Ignore the case of the words to find more unique words. e.g. (A === a, Hello === hello)
-
-3. Order the results to find out which word is the most common in the input
-*/
+module.exports = countWords;

Sprint-2/stretch/mode.js

@@ -1,36 +1,34 @@
-// You are given an implementation of calculateMode
+function trackFrequencies(list) {
+  const freqs = new Map();
 
-// calculateMode's implementation can be broken down into two stages:
-
-// Stage 1. One part of the code tracks the frequency of each value
-// Stage 2. The other part finds the value with the highest frequency
-
-// refactor calculateMode by splitting up the code
-// into smaller functions using the stages above
-
-function calculateMode(list) {
-  // track frequency of each value
-  let freqs = new Map();
-
-  for (let num of list) {
+  for (const num of list) {
     if (typeof num !== "number") {
       continue;
     }
 
     freqs.set(num, (freqs.get(num) || 0) + 1);
   }
 
-  // Find the value with the highest frequency
+  return freqs;
+}
+
+function findMode(freqs) {
   let maxFreq = 0;
   let mode;
-  for (let [num, freq] of freqs) {
+
+  for (const [num, freq] of freqs) {
     if (freq > maxFreq) {
-      mode = num;
       maxFreq = freq;
+      mode = num;
     }
   }
 
   return maxFreq === 0 ? NaN : mode;
 }
 
+function calculateMode(list) {
+  const freqs = trackFrequencies(list);
+  return findMode(freqs);
+}
+
 module.exports = calculateMode;