Let's practice!

Exercise - Implement Peek

Your task is to implement the peek() method of the Stack class. The peek() method lets you see what is on the top of the stack without actually removing it from the stack (like pop()) does. So when you call it, what it should return is either null if the stack is empty or the top element if it isn't.

For example, if your queue were [4,6,1,9], peek would return 9.

Start here

...Hint 🙈 Pseudo-code: ```js if this.array is empty, return null var lastElement = getLastElementFrom(this.array); return lastElement; ```

Solution

Exercise - Implement isEmpty

Your task is to implement the isEmpty() method of the Stack class. This method tells you whether the Stack is empty or not. It will return true or false.

Start here

...Hint 🙈 Pseudo-code: ```js if this.array has a length of 0, return true else return false ```

Solution

Congratulations! You've made an entire stack data structure. As a recap, the methods here are:

  • push() - Adds to the top of the stack
  • pop() - Removes from the top of the stack
  • peek() - Gives you the value at the top of the stack without removing it
  • isEmpty() - Determines whether the stack is empty or not

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