Complete search and replace algorithm

Author: ahcode0919

src/fcc-intermediate-algorithms/fcc-intermediate-algorithms.md

@@ -10,6 +10,7 @@ From the Freecodecamp Javascript Certification Intermediate Algorithms module
 - [Wherefore Art Thou](#wherefore-art-thou)
 - [Spinal Tap Case](#spinal-tap-case)
 - [Pig Latin](#pig-latin)
+- [Search and Replace](#search-and-replace)
 
 #### Sum All Numbers In a Range
 
@@ -102,7 +103,35 @@ export function translatePigLatin(str) {
         return str + 'way';
     }
 
-    let splitStr = str.split(/([aeiou].*)/)
+    const splitStr = str.split(/([aeiou].*)/);
     return [splitStr[1], splitStr[0], 'ay'].join('');
 }
 ```
+
+#### Search and Replace
+
+Perform a search and replace on the sentence using the arguments provided and return the new sentence.
+
+First argument is the sentence to perform the search and replace on.
+
+Second argument is the word that you will be replacing (before).
+
+Third argument is what you will be replacing the second argument with (after).
+
+Note
+Preserve the case of the first character in the original word when you are replacing it. For example if you mean to replace the word "Book" with the word "dog", it should be replaced as "Dog"
+
+```javascript
+export function myReplace(str, before, after) {
+    const indexOfInsert = str.indexOf(before);
+    const preInsert = str.slice(0, indexOfInsert);
+    const postInsert = str.slice(indexOfInsert + before.length);
+
+    if (/^[A-Z]/.test(before)) {
+        const capitalizedAfter = after.charAt(0).toUpperCase() + after.slice(1);
+        return [preInsert, capitalizedAfter, postInsert].join('');
+    }
+
+    return [preInsert, after, postInsert].join('');
+}
+```

src/fcc-intermediate-algorithms/pig_latin.js

@@ -2,11 +2,11 @@ export function translatePigLatin(str) {
     if (str === "") {
         return "";
     }
-    
+
     if (/^[aeiou]/.test(str)) {
         return str + 'way';
     }
 
-    let splitStr = str.split(/([aeiou].*)/)
+    const splitStr = str.split(/([aeiou].*)/);
     return [splitStr[1], splitStr[0], 'ay'].join('');
 }

src/fcc-intermediate-algorithms/search_and_replace.js

@@ -0,0 +1,12 @@
+export function myReplace(str, before, after) {
+    const indexOfInsert = str.indexOf(before);
+    const preInsert = str.slice(0, indexOfInsert);
+    const postInsert = str.slice(indexOfInsert + before.length);
+    
+    if (/^[A-Z]/.test(before)) {
+        const capitalizedAfter = after.charAt(0).toUpperCase() + after.slice(1);
+        return [preInsert, capitalizedAfter, postInsert].join('');
+    }
+    
+    return [preInsert, after, postInsert].join('');
+}

tests/fcc-intermediate-algorithms/search_and_replace.test.js

@@ -0,0 +1,6 @@
+import { myReplace } from "../../src/fcc-intermediate-algorithms/search_and_replace";
+
+test('should replace the specified word', () => {
+    expect(myReplace("His name is Tom", "Tom", "john")).toBe("His name is John");
+    expect(myReplace("The boat is red", "red", "blue")).toBe("The boat is blue");
+});