Create Stack2.js

Author: HansUXdev

03-DataStructures/Stack2.js

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+
+// Here's an example of a Stack class in JavaScript without using built-in functions, including explanations for educational purposes:
+
+class Stack {
+    constructor() {
+      this.items = [];
+      this.top = -1;
+    }
+  
+    // Custom method to add an item at the end of the array
+    _append(item) {
+      this.top++;
+      this.items[this.top] = item;
+    }
+  
+    // Custom method to remove the last item from the array
+    _removeLast() {
+      const removedItem = this.items[this.top];
+      this.top--;
+      return removedItem;
+    }
+  
+    // Add an item to the top of the stack
+    push(item) {
+      this._append(item);
+    }
+  
+    // Remove and return the item at the top of the stack
+    pop() {
+      if (this.isEmpty()) {
+        throw new Error("Stack is empty");
+      }
+      return this._removeLast();
+    }
+  
+    // Return the item at the top of the stack without removing it
+    peek() {
+      if (this.isEmpty()) {
+        throw new Error("Stack is empty");
+      }
+      return this.items[this.top];
+    }
+  
+    // Check if the stack is empty
+    isEmpty() {
+      return this.top === -1;
+    }
+  
+    // Return the number of items in the stack
+    size() {
+      return this.top + 1;
+    }
+  
+    // Empty the stack
+    clear() {
+      this.items = [];
+      this.top = -1;
+    }
+  }
+  
+  // Example usage:
+  const stack = new Stack();
+  stack.push(10);
+  stack.push(20);
+  stack.push(30);
+  console.log(stack.peek()); // 30
+  stack.pop();
+  console.log(stack.peek()); // 20
+