feat: adds LJs code samples in JS and Java to find prime numbers (#142)

* Initial commit of program files. Created java scanner. WIP

* finished java program. changed variable name for Scanner. added comments for clarity.

* populated the JS file. Implemented Node.js and added comments for clarity

* added explanation readme file

Author: marleomac3

lesson_04/ljmcwilliams/README.md

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+In this lesson, I explored the differences between Java and JavaScript. Despite their similar names, these languages have distinct features.
+
+- ## Key Differences
+- ### Document Preparation:
+
+    - Java requires preparation before defining variables and functions.
+JavaScript has more flexibility with variable definitions.
+
+- ### User Input:
+
+    - In Java, I used the Scanner class to prompt the user for number input.
+This required importing Java's Scanner class.
+In JavaScript, there is no built-in Scanner class, so I used Node.js as a workaround.
+With Node.js, I utilized process.stdin for input and process.stdout for output (similar to console.log).
+
+- ### Loop Control:
+
+    - Both languages allow for loops to be exited early, but the methods differ:
+In Java, using a break statement within the loop will terminate it.
+In JavaScript, I opted for read.close(), which achieves a similar effect.
+
+- ### Variable Declaration:
+
+    - Java requires explicit declaration of variable types.
+JavaScript automatically assigns variable types.
+- ## Loop Behavior
+Both languages share similarities in loop functionality:
+
+- **For Loops**:
+    - Take three expressions.
+
+- **If Statements**:
+    - Accept a condition and can be nested.
+
+- **Java Example**
+```java
+for (int i = 2; i < userInput; i++) {
+            if ((userInput / i) == (int) (userInput / i)) {
+                System.out.println(userInput + " is not a prime number.");
+                isConditionMet = true;
+                break;
+            }
+        } if (!isConditionMet) {
+            System.out.println(userInput + " is a prime number.");
+        }
+```
+- **JavaScript Example**
+```javascript
+for (let i = 2; i < answer; i++) {
+            if ((answer / i) == parseInt(answer / i)) {
+                console.log(answer + " is not a prime number.");
+                isConditionMet = true;
+                read.close();
+            }
+        } if (!isConditionMet) {
+            console.log(answer + " is a prime number.");
+            read.close();
+        }
+```

lesson_04/ljmcwilliams/findPrimeNum.java

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+import java.util.Scanner; //This allows us to use the scanner to take in user input
+public class findPrimeNum {
+    public static void main(String[] args) {
+        Scanner objScanner = new Scanner(System.in); //A scanner named 'objScanner'
+        boolean isConditionMet = false; 
+
+        /*if the condition is met, the print statement within the loop will be printed. 
+        If not, the print statement after the loop will be printed*/
+
+        System.out.print("Please enter a whole number: "); //User input prompt
+        double userInput = objScanner.nextDouble(); //This reads an integer value from the user
+
+        /*to determine a number's primality, we can check to see if the division 
+        of that number by 2 to (1 - that number) results in any whole number quotients.
+        Once we do the division we can compare that number to (int) number to see if the
+        values are equal.*/
+
+        /*the program should end if A: the first whole number quotient is found, indicating that
+         * indicating a number is not prime or if B: no whole number quotients are found within the
+         * range indicating the number IS prime.*/
+        
+         for (int i = 2; i < userInput; i++) {
+            if ((userInput / i) == (int) (userInput / i)) {
+                System.out.println(userInput + " is not a prime number.");
+                isConditionMet = true;
+                break; //this helps jump out of the loop once this first whole number quotient instace is found
+            }
+        } if (!isConditionMet) {
+            System.out.println(userInput + " is a prime number.");
+        }
+    }
+}

lesson_04/ljmcwilliams/findPrimeNum.js

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+const readline = require('readline'); //"require()" imports the readline module which will process the user input
+const read = readline.createInterface({
+    input: process.stdin, //this acts as an input scanner
+    output: process.stdout //this works like a normal console.log combined with a user's input
+});
+let isConditionMet = false;
+
+/* When looking at the Node.js docs, it states '.question()' displays the query (in this case the user prompt).
+It waits for an input and uses it as the first argument in a callback function (here I am using a arrow function). */
+read.question("Enter a number: ", (answer) => {
+    for (let i = 2; i < answer; i++) {
+            if ((answer / i) == parseInt(answer / i)) { //similar to the "(int)" statement in java, parseInt converts doubles to ints
+                console.log(answer + " is not a prime number.");
+                isConditionMet = true;
+                read.close(); //this works similar to a break statement in java and ends the program
+            }
+        } if (!isConditionMet) {
+            console.log(answer + " is a prime number.");
+            read.close();
+        }
+})