Eloquent Javascript Problems

chapter04.js

@@ -10,41 +10,122 @@
 // Problem 1: The sum of a range
 function range(start, end, step=1) {
   // Your code here
+  let arr = [];
+
+  if (step > 0) {
+    for (let i = start; i <= end; i += step) {
+      arr.push(i);
+    }
+  }
+
+  if (step < 0) {
+    for (let i = start; i >= end; i += step) {
+      arr.push(i);
+    }
+  }
+
+  return arr;
+
 }
 
 function sum(array) {
   // Your code here
+  let sum = 0;
+  array.forEach((x) => { sum += x;});
+
+  return sum;
 }
 
 // Problem 2: Reversing an Array
 function reverseArray(array) {
   // Your code here
+  let arr = [];
+  const arrayLength = array.length;
+
+  for (let i = arrayLength - 1; i >= 0; i -= 1) {
+    arr.push(array[i]);
+  }
+
+  return arr;
 }
 
 function reverseArrayInPlace(array) {
   // Your code here
+  const arrLength = array.length;
+  for (let s = 0, e = arrLength-1; s < e;) {
+    let a = array[s];
+    array[s] = array[e];
+    array[e] = a;
+
+    s += 1;
+    e -= 1;
+  }
+
+  return array;
 }
 
 // Problem 3: A List
 function arrayToList(array) {
   // Your code here
+  var v = array[0];
+  array.splice(0, 1);
+
+  if (array.length === 0) {
+    return {value: v, rest: null};
+  }
+
+  return {value: v, rest: arrayToList(array)}
 }
 
 function listToArray(list) {
   // Your code here
+  var arr  = [];
+  while (list !== null) {
+    arr.push(list.value)
+    list = list.rest;
+  }
+
+  return arr;
 }
 
 function nth(list, position) {
   // Your code here
+  if (list === null) {
+    return null;
+  }
+  if (position === 0) {
+    return list.value;
+  }
+
+  list = list.rest;
+  position -= 1;
+  return nth(list, position);
 }
 
 function prepend(element, list) {
   // Your code here
+  var head = {value: element, rest: list};
+
+  return head;
 }
 
 // Problem 4: Deep comparison
 function deepEqual(obj1, obj2) {
   // Your code here
+  if ((typeof(obj1) === "object" && typeof(obj1) !== null) && (typeof(obj2) === "object" && typeof(obj2) !== null)) {
+    for (var x in obj1) {
+      if (obj2.hasOwnProperty(x)) {
+        if (!deepEqual(obj1[x], obj2[x])) {
+          return false;
+        }
+      } else {
+        return false;
+      }
+    } 
+  } else if (obj1 !== obj2) {
+    return false;
+  }
+  return true;
 }
 
 

chapter05.js

@@ -21,12 +21,26 @@ ancestry.forEach(function(person) {
 // Problem 1: Flattening
 function flatten(arrays) {
   // Your code here
+  var newArray = arrays.reduce((x, y) => {return x.concat(y);});
+  return newArray;
 }
 
 // Problem 2: Mother-child age difference
 /* This must return the average age difference instead of printing it */
 function averageMomChildAgeDiff() {
   // Your code here
+  var ageDiffs = []
+  for (person in byName) {
+  	var child = byName[person];
+  	if (child.mother) {
+  		var mother = byName[child.mother];
+  		if (mother) {
+  			ageDiffs.push(child.born - mother.born);
+  		}
+  	}
+  }
+
+  return average(ageDiffs);
 }
 
 // Problem 3: Historical life expectancy
@@ -35,6 +49,22 @@ function averageMomChildAgeDiff() {
  */
 function averageAgeByCentury() {
   // Your code here
+  var ageGroups = {};
+  for (person in byName) {
+  	var century = Math.ceil(byName[person].died / 100);
+  	var personAge = byName[person].died - byName[person].born
+  	if (ageGroups[century]) {
+  		ageGroups[century].push(personAge);
+  	} else {
+  		ageGroups[century] = [personAge];
+  	}
+  }
+
+  for (group in ageGroups) {
+  	ageGroups[group] = average(ageGroups[group]);
+  }
+
+  return ageGroups;
 }
 
 

chapter13.js

@@ -10,6 +10,28 @@
 // Problem 1: Build table
 function buildTable(data) {
   // Your code here
+  var table = document.createElement('table');
+  var headerRow = document.createElement('tr');
+
+  for (header in data[0]) {
+  	var th = document.createElement('th');
+  	th.textContent = header;
+  	headerRow.appendChild(th);
+  }
+  table.appendChild(headerRow);
+
+  data.forEach(d => {
+  	var row = document.createElement('tr');
+
+  	for (prop in d) {
+  		var td = document.createElement('td');
+  		td.textContent = d[prop];
+  		row.appendChild(td);
+  	}
+  	table.appendChild(row);
+  });
+
+  return table;
 }