Update with longestString complete.

isUnique/isUnique.js

@@ -1,3 +1,14 @@
 /* Implement an algorithm to determine if a string has all unique characters.
  * What if you cannot use additional data structures?
- */
+ */
+
+ const isUnique = (str) => {
+	let currentChar = str.charAt(0);
+	for(let i = 1; i < str.length; i++) {
+		let newChar = str.charAt(i);
+		if(currentChar === newChar) {
+			return false;
+		}
+	}
+	return true;
+};

longestString/longestString.js

@@ -2,3 +2,13 @@
  * Write a function that accepts an array of strings.
  * Return the longest string in the array.
  */
+
+const longestString = (stringArray) => {
+	let currentLongest = stringArray[0];
+	for(strings of stringArray) {
+		if(strings.length > currentLongest.length) {
+			currentLongest = strings;
+		}
+	}
+	return currentLongest;
+}

reverseCase/reverseCase.js

@@ -2,4 +2,19 @@
  * Write a function that reverses the case of each letter in the strings that it receives.
  * Example: 'Hello World' -> 'hELLO wORLD'
  * Assume that each string will contain only spaces and letters.
- */
+ */
+
+ const reverseCase = (str) => {
+  let newString = '';
+  for (let i = 0; i < str.length; i++) {
+  	let character = str.charCodeAt(i);
+    if ((character >= 65) && (character <= 90)) {
+    	newString = newString + (str.charAt(i).toLowerCase());
+    } else if ((str.charCodeAt(i) >= 97) && (str.charCodeAt(i) <= 122)) {
+    	newString = newString + (str.charAt(i).toUpperCase());
+    } else {
+    newString = newString + ' ';
+    }
+  }
+  return newString;
+}