Ready for Review

StringsAndTings.js

@@ -1,28 +1,65 @@
 class StringsAndTings {
-    
+
     // @return string with identical content, and the first character capitalized
-    camelCase(str){
-        return null;
+    camelCase(str) {
+        let result = "";
+        for (let i = 0; i < str.length; i++) {
+            if (i == 0 || str[i - 1] == " ") {
+                result += str[i].toUpperCase();
+            } else {
+                result += str[i];
+            }
+        }
+        return result;
+    }
+
+    reverseString(str) {
+        // Strings in js are immutable. Need to split it into a new array to modify it.
+        let result = str.split("");
+        let length = result.length;
+        // You would think you'd need to subtract 1 from here, but that does not work. This method seems to work for even and odd lengthed inputs.
+        const halfLength = Math.floor(length / 2);
+        for (let i = 0; i < halfLength; i++) {
+            let rightLetter = result[length - i - 1];
+            result[length - i - 1] = result[i];
+            result[i] = rightLetter;
+        }
+        return result.join("").toString();
     }
 
-    //@return string with identical contents, with each word individually in reverse order
-    reverseString(str){
-        return null;
+    reverseWords(str) {
+        let result = "";
+        let words = str.split(" ");
+        for (let word of words) {
+            word = this.reverseString(word);
+            result += `${word} `;
+        }
+        return result.trim();
     }
 
     // @return string with identical contents, in reverse order, with first character capitalized
-    reverseThenCamelCase(str){
-        return null;
+    reverseThenCamelCase(str) {
+        const reversedStr = this.reverseString(str);
+        return this.camelCase(reversedStr);
     }
 
     // @return string with identical contents excluding first and last character
-    removeFirstAndLastCharacter(str){
-        return null;
+    removeFirstAndLastCharacter(str) {
+        // Use str.length - 1 because it returns the value *up to* that index, not *at* that index. So return value up to the very last index.
+        return str.substring(1, str.length - 1)
     }
 
     // @return string with identical characters, each with opposite casing
-    invertCasing(str){
-        return null;
+    invertCasing(str) {
+        let result = "";
+        for (let c of str) {
+            if (c == c.toUpperCase()) {
+                result += c.toLowerCase();
+            } else {
+                result += c.toUpperCase();
+            }
+        }
+        return result;
     }
 }
 

StringsAndTings.test.js

@@ -8,7 +8,7 @@ test("camelCaseTest", () => {
     let input = "she sells sea shells";
     let expected = "She Sells Sea Shells";
 
-    let actual = stringsAndTings.camelCase(15);
+    let actual = stringsAndTings.camelCase(input);
 
     expect(actual).toEqual(expected);
 });
@@ -19,7 +19,7 @@ test("reverseTest", () => {
     let input = "she sells sea shells";
     let expected = "sllehs aes slles ehs";
 
-    let actual = stringsAndTings.camelCase(15);
+    let actual = stringsAndTings.reverseString(input);
 
     expect(actual).toEqual(expected);
 });
@@ -30,7 +30,7 @@ test("reverseWordsTest", () => {
     let input = "she sells sea shells";
     let expected = "ehs slles aes sllehs";
 
-    let actual = stringsAndTings.camelCase(15);
+    let actual = stringsAndTings.reverseWords(input);
 
     expect(actual).toEqual(expected);
 });
@@ -41,7 +41,7 @@ test("reverseThenCamelCaseTest", () => {
     let input = "she sells sea shells";
     let expected = "Sllehs Aes Slles Ehs";
 
-    let actual = stringsAndTings.camelCase(15);
+    let actual = stringsAndTings.reverseThenCamelCase(input);
 
     expect(actual).toEqual(expected);
 });
@@ -52,7 +52,7 @@ test("removeFirstAndLastCharacterTest", () => {
     let input = "she sells sea shells";
     let expected = "he sells sea shell";
 
-    let actual = stringsAndTings.camelCase(15);
+    let actual = stringsAndTings.removeFirstAndLastCharacter(input);
 
     expect(actual).toEqual(expected);
 });
@@ -64,7 +64,7 @@ test("invertCasingTest1", () => {
     let input = "shE sells SEA sHeLlS";
     let expected = "SHe SELLS sea ShElLs";
 
-    let actual = stringsAndTings.camelCase(15);
+    let actual = stringsAndTings.invertCasing(input);
 
     expect(actual).toEqual(expected);
 });