Feature/week 4 exercises

week-4/implement/count.test.js

@@ -1,4 +1,7 @@
-// implement a function countChar that counts the number of times a character occurs in a string
+
+// Given the input string str,
+// And a character char that does not exist within the case-sensitive str,
+// When the function is called with these inputs,// implement a function countChar that counts the number of times a character occurs in a string
 
 // Given a string str and a single character char to search for,
 // When the countChar function is called with these inputs,
@@ -11,7 +14,39 @@
 // Then it should correctly count consecutive occurrences of char (e.g., 'a' appears five times in 'aaaaa').
 
 // Scenario: No Occurrences
-// Given the input string str,
-// And a character char that does not exist within the case-sensitive str,
-// When the function is called with these inputs,
 // Then it should return 0, indicating that no occurrences of the char were found in the case-sensitive str.
+function countChar(str,char){
+  let count = 0;
+  for(let i=0; i<str.length; i++){
+    if(str[i] === char){
+        count++;
+    }
+  }
+  return count;
+}
+console.log(countChar("aaaaa","a"));  // Expected output :5
+console.log(countChar("banana", "a")); // Expected output: 3
+
+// Scenario: No Occurrences
+console.log(countChar("hello", "z")); // Expected output: 0
+console.log(countChar("world", "a")); // Expected output: 0
+
+// Edge cases
+console.log(countChar("", "a"));       // Expected output: 0 (empty string)
+console.log(countChar("a", "a"));      // Expected output: 1 (single character match)
+console.log(countChar("AaAaA", "A")); 
+
+// assertions
+console.assert(countChar("aaaaa", "a") === 5, "Test 1 Failed: Expected 5 for input ('aaaaa', 'a')");
+console.assert(countChar("banana", "a") === 3, "Test 2 Failed: Expected 3 for input ('banana', 'a')");
+
+// Scenario: No Occurrences
+console.assert(countChar("hello", "z") === 0, "Test 3 Failed: Expected 0 for input ('hello', 'z')");
+console.assert(countChar("world", "a") === 0, "Test 4 Failed: Expected 0 for input ('world', 'a')");
+
+// Edge cases
+console.assert(countChar("", "a") === 0, "Test 5 Failed: Expected 0 for empty string input ('', 'a')");
+console.assert(countChar("a", "a") === 1, "Test 6 Failed: Expected 1 for input ('a', 'a')");
+console.assert(countChar("AaAaA", "A") === 3, "Test 7 Failed: Expected 3 for case-sensitive input ('AaAaA', 'A')");
+
+console.log("All tests passed!");

week-4/implement/credit-card-vslidator.js

@@ -0,0 +1,26 @@
+function creditCard(value){
+    const cardPattern = /^\d{16}$/.test(value);
+    if(!cardPattern){
+      return "Invalid: Must be 16 digits and all numbers";
+    }
+     const uniqueDigits = new Set(value.split('')).size;
+    if (uniqueDigits < 2) {
+        return "Invalid: Must contain at least two different digits";
+    }
+    if(parseInt(value.slice(-1)) % 2 !== 0){
+        return "Invalid: Final digit must be even";
+    }
+    const sum = Array.from(value).reduce((a,b) => a+parseInt(b),0);
+    if(sum <=16){
+      return "Invalid: Sum of all digits must be greater than 16";
+    }
+      return "Valid credit card number";
+
+}
+// Example tests
+console.log(creditCard("9999777788880000")); // "Valid credit card number"
+console.log(creditCard("6666666666661666")); // "Valid credit card number"
+console.log(creditCard("a92332119c011112")); // "Invalid: Must be 16 digits and all numbers"
+console.log(creditCard("4444444444444444")); // "Invalid: Must contain at least two different digits"
+console.log(creditCard("1111111111111110")); // "Invalid: Sum of all digits must be greater than 16"
+console.log(creditCard("6666666666666661")); //  "Invalid: Final digit must be even"

week-4/implement/get-ordinal-number.test.js

@@ -2,3 +2,18 @@
 
 // continue testing and implementing getOrdinalNumber for additional cases
 // Write your tests using Jest - remember to run your tests often for continual feedback
+function getOrdinal(number){
+    const suffixes = ["th","st","nd","rd"];
+    const value = number % 100;
+    const sufix = (value > 10 && value <20) ? suffixes[0] : suffixes[Math.min(value%10,3)];
+    return value+sufix;
+}
+console.log(getOrdinal(1));   // "1st"
+console.log(getOrdinal(2));   // "2nd"
+console.log(getOrdinal(3));   // "3rd"
+console.log(getOrdinal(4));   // "4th"
+console.log(getOrdinal(11));  // "11th"
+console.log(getOrdinal(21));  // "21st"
+console.log(getOrdinal(42));  // "42nd"
+console.log(getOrdinal(103)); // "103rd"
+console.log(getOrdinal(112)); // "112th"

week-4/implement/is-prime.test.js

@@ -1,3 +1,26 @@
 // Given a positive integer num,
 // When the isPrime function is called with num as input,
 // Then it should return a boolean representing whether the num is prime
+function isPrime(num){
+    if(num <=1){
+        return false;
+    }
+    if(num === 2){
+        return true;
+    }
+    if(num % 2 === 0){
+        return false;
+    }
+    for(let i=3; i<=Math.sqrt(num); i++){
+        if(num % i === 0){
+            return false;
+        }
+    }
+    return true;
+}
+console.log(isPrime(2));   // true
+console.log(isPrime(11));  // true
+console.log(isPrime(15));  // false
+console.log(isPrime(1));   // false
+console.log(isPrime(17));  // true
+console.log(isPrime(25));  // false

week-4/implement/password-validator.test.js

@@ -14,3 +14,35 @@ To be valid, a password must:
 
 You must breakdown this problem in order to solve it. Find one test case first and get that working
 */
+function validPassword(pass){
+    if(pass < 5){
+        return "Error: Password must have at least 5 characters";
+    }
+    else if(!/[A-Z]/.test(pass)){
+         return "Error: Password must contain at least one uppercase letter (A-Z)";
+    }
+    else if(!/[a-z]/.test(pass)){
+          return "Error: Password must contain at least one lowercase letter (a-z)";
+    }
+    else if(!/[0-9]/.test(pass)){
+         return "Error: Password must contain at least one number(0-9)";
+    }
+    else if(!/[!#$%.*&]/.test(pass)){
+         return "Error: password at least one non-alphanumeric symbol";
+    }
+    else if(previousPasswords.includes(pass)){
+         return "Error: Password must not be any of the previous passwords";
+    }
+    else{
+         return "Password is valid";
+    }
+}
+const previousPasswords = ["Password123!", "abcDE1$", "Valid1$"];
+console.log(validPassword("Abcde", previousPasswords));         // "Error: Password must contain at least one number (0-9)"
+console.log(validPassword("ABCDE", previousPasswords));         // "Error: Password must contain at least one lowercase letter (a-z)"
+console.log(validPassword("abcd1", previousPasswords));         // "Error: Password must have at least 5 characters"
+console.log(validPassword("Valid1$", previousPasswords));       // "Error: Password must not be any of the previous passwords"
+console.log(validPassword("lowercase1$", previousPasswords));   // "Error: Password must contain at least one uppercase letter (A-Z)"
+console.log(validPassword("12345!", previousPasswords));        // "Error: Password must contain at least one uppercase letter (A-Z)"
+console.log(validPassword("Valid1$", previousPasswords));       // "Error: Password must not be any of the previous passwords"
+console.log(validPassword("NewPass1$", previousPasswords));     // password is valid

week-4/implement/repeat.test.js

@@ -23,3 +23,25 @@
 // Given a target string str and a negative integer count,
 // When the repeat function is called with these inputs,
 // Then it should throw an error or return an appropriate error message, as negative counts are not valid.
+function repeat(str,count){
+ if(count < 0){
+    throw new Error("Count must be a positive integer.");
+ }
+ if(count === 0){
+    return "";
+ }
+ if(count === 1){
+    return str;
+ }
+ if(count >1){
+    return str.repeat(count);
+ }
+}
+ console.log(repeat("hello", 3));
+ console.log(repeat("world", 1)); 
+try {
+    console.log(repeat("test", 0));   
+    console.log(repeat("error", -2)); 
+} catch (Error) {
+    console.error(Error.message);
+}

week-4/investigate/find.js

@@ -20,6 +20,13 @@ console.log(find("code your future", "z"));
 // Pay particular attention to the following:
 
 // a) How the index variable updates during the call to find
+//    the index value at start is 0 and string "code your future" = 16 so index value is ++ according to the condition
+
 // b) What is the if statement used to check
+//   until str[index] === "u" because U is at position 7 so it returns 7
+
 // c) Why is index++ being used?
+//   in each iteration the value of index is inx=creased by one until the condition is true
+
 // d) What is the condition index < str.length used for?
+//    str.length means that the it takes string length that is total is 17 in this case