diff --git a/01-js/easy/anagram.js b/01-js/easy/anagram.js
index fff61427..b4904773 100644
--- a/01-js/easy/anagram.js
+++ b/01-js/easy/anagram.js
@@ -8,7 +8,12 @@
 */
 
 function isAnagram(str1, str2) {
+  var st1=str1.toLowerCase();
+  var st2= str2.toLowerCase();
 
+  if(st1.split('').sort().join('') === st2.split('').sort().join('')) return true;
+  
+  else return false;
 }
 
 module.exports = isAnagram;
diff --git a/01-js/easy/expenditure-analysis.js b/01-js/easy/expenditure-analysis.js
index 20fbb943..a8d9a69f 100644
--- a/01-js/easy/expenditure-analysis.js
+++ b/01-js/easy/expenditure-analysis.js
@@ -9,7 +9,31 @@
 */
 
 function calculateTotalSpentByCategory(transactions) {
-  return [];
+
+  var categories={};
+
+  var output=[];
+
+  for(var item of transactions)
+  {
+    if(categories[item.category])
+    {
+      categories[item.category]=categories[item.category]+item.price
+    }
+
+    else
+    {
+      categories[item.category] = item.price;
+    }
+  }
+
+  for(var price in categories)
+  {
+    output.push({category: price, totalSpent: categories[price]});
+  }
+
+  return output;
+
 }
 
 module.exports = calculateTotalSpentByCategory;
diff --git a/01-js/hard/calculator.js b/01-js/hard/calculator.js
index 82d48229..b341e4ac 100644
--- a/01-js/hard/calculator.js
+++ b/01-js/hard/calculator.js
@@ -17,6 +17,59 @@
   - `npm run test-calculator`
 */
 
-class Calculator {}
+class Calculator {
+
+  constructor()
+  {
+    this.result=0;
+  }
+
+  add(num)
+  {
+    this.result=this.result+num;
+  }
+  subtract(num)
+  {
+    this.result=this.result-num;
+  }
+  multiply(num)
+  {
+    this.result=this.result*num;
+  }
+  divide(num)
+  {
+    if (num === 0) {
+      throw new Error("Cannot divide by zero");
+    }
+    this.result=this.result/num;
+  }
+  clear()
+  {
+    this.result=0;
+  }
+  getResult()
+  {
+    return this.result;
+  }
+  calculate(expression) {
+    expression = expression.replace(/\s+/g, '');
+  
+    if (!/^[0-9+\-*/().]+$/.test(expression)) {
+      throw new Error("Invalid expression");
+    }
+
+    try {
+      // Check for division by zero
+      if (expression.includes('/0')) {
+        throw new Error("Cannot divide by zero");
+      }
+
+      this.result = eval(expression);
+    } catch (error) {
+      throw new Error("Invalid expression");
+  }
+  }
+
+}
 
 module.exports = Calculator;
diff --git a/01-js/hard/todo-list.js b/01-js/hard/todo-list.js
index 7c9c1806..e28d666a 100644
--- a/01-js/hard/todo-list.js
+++ b/01-js/hard/todo-list.js
@@ -13,6 +13,39 @@
 
 class Todo {
 
+  constructor()
+  {
+    this.todos=[];
+  }
+
+  add(todo)
+  {
+    this.todos.push(todo);
+  }
+
+  remove(ind)
+  {
+    if(ind>=0 && ind< this.todos.length) this.todos.splice(ind,1);
+  }
+
+  update(ind,newTodo)
+  {
+    if(ind>=0 && ind< this.todos.length) this.todos[ind]= newTodo;
+  }
+  getAll()
+  {
+    return this.todos;
+  }
+  get(ind)
+  {
+    if(ind>=0 && ind< this.todos.length) return this.todos[ind];
+
+    return null;
+  }
+  clear()
+  {
+    this.todos=[];
+  }
 }
 
 module.exports = Todo;
diff --git a/01-js/medium/palindrome.js b/01-js/medium/palindrome.js
index d8fe2d8f..b11d4ea0 100644
--- a/01-js/medium/palindrome.js
+++ b/01-js/medium/palindrome.js
@@ -7,6 +7,23 @@
 */
 
 function isPalindrome(str) {
+  var lstr=str.toLowerCase();
+  lstr = lstr.replaceAll(" ","");
+
+  var n=lstr.length;
+  var i=0,j=n-1;
+
+  while(i<j)
+  {
+    if(lstr[i]<'a' || lstr[i]>'z')i++;
+    if(lstr[j]<'a' || lstr[j]>'z')j--;
+
+    if(lstr[i]!= lstr[j]) return false;
+
+    i++;
+    j--;
+  }
+
   return true;
 }
 
diff --git a/01-js/medium/times.js b/01-js/medium/times.js
index eb125cc2..3ccf597f 100644
--- a/01-js/medium/times.js
+++ b/01-js/medium/times.js
@@ -8,5 +8,16 @@ Hint - use Date class exposed in JS
 */
 
 function calculateTime(n) {
-    return 0.01;
-}
\ No newline at end of file
+    var sum=0;
+
+    var curr= parseFloat(Date.now());
+    for(var i=1; i<=n; i++)
+    {
+        sum+=i;
+    }
+    var ncurr= parseFloat(Date.now());
+
+    return parseFloat(ncurr-curr);
+}
+
+console.log(calculateTime(10000000));
\ No newline at end of file