Mean median mode algorithm

Author: dhimasanb

Algorithm/meanMedianMode.js

@@ -0,0 +1,61 @@
+function meanMedianMode(arr) {
+  return {
+    mean: getMean(arr),
+    median: getMedian(arr),
+    mode: getMode(arr)
+  };
+}
+
+function getMean(arr) {
+  let sum = 0;
+
+  arr.forEach(num => {
+    sum += num;
+  });
+
+  let mean = sum / arr.length;
+  return mean;
+}
+
+function getMedian(arr) {
+  arr.sort(function(a, b) {
+    return a - b;
+  });
+  let median;
+
+  if (arr.length % 2 !== 0) {
+    median = arr[Math.floor(arr.length / 2)];
+  } else {
+    let mid1 = arr[arr.length / 2 - 1];
+    let mid2 = arr[arr.length / 2];
+    median = (mid1 + mid2) / 2;
+  }
+
+  return median;
+}
+
+function getMode(arr) {
+  let modeObj = {};
+
+  arr.forEach(num => {
+    if (!modeObj[num]) modeObj[num] = 0;
+    modeObj[num]++;
+  });
+
+  let maxFrequency = 0;
+  let modes = [];
+  for (let num in modeObj) {
+    if (modeObj[num] > maxFrequency) {
+      modes = [num];
+      maxFrequency = modeObj[num];
+    } else if (modeObj[num] === maxFrequency) modes.push(num);
+  }
+
+  if (modes.length === Object.keys(modeObj).length) modes = [];
+
+  return modes;
+}
+
+meanMedianMode([1, 2, 3, 4, 5, 4, 6, 1]); // { mean: 3.25, median: 3.5, mode: [ '1', '4' ] }
+
+meanMedianMode([9, 10, 23, 10, 23, 9]); //  mean: 14, median: 10, mode: [] }