80 lines
4.0 KiB
Markdown
80 lines
4.0 KiB
Markdown
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---
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id: 587d8250367417b2b2512c5f
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title: Create a Stack Class
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challengeType: 1
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---
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## Description
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<section id='description'>
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In the last section, we talked about what a stack is and how we can use an array to represent a stack. In this section, we will be creating our own stack class.
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Although you can use arrays to create stacks, sometimes it is best to limit the amount of control we have with our stacks.
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Apart from the <code>push</code> and <code>pop</code> method, stacks have other useful methods. Let's add a <code>peek</code>, <code>isEmpty</code>, and <code>clear</code> method to our stack class.
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Instructions
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Write a <code>push</code> method that pushes an element to the top of the stack, a <code>pop</code> method that removes the element on the top of the stack, a <code>peek</code> method that looks at the first element in the stack, an <code>isEmpty</code> method that checks if the stack is empty, and a <code>clear</code> method that removes all elements from the stack.
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Normally stacks don't have this, but we've added a <code>print</code> helper method that console logs the collection.
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</section>
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## Instructions
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<section id='instructions'>
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: Your <code>Stack</code> class should have a <code>push</code> method.
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testString: 'assert((function(){var test = new Stack(); return (typeof test.push === ''function'')}()), ''Your <code>Stack</code> class should have a <code>push</code> method.'');'
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- text: Your <code>Stack</code> class should have a <code>pop</code> method.
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testString: 'assert((function(){var test = new Stack(); return (typeof test.pop === ''function'')}()), ''Your <code>Stack</code> class should have a <code>pop</code> method.'');'
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- text: Your <code>Stack</code> class should have a <code>peek</code> method.
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testString: 'assert((function(){var test = new Stack(); return (typeof test.peek === ''function'')}()), ''Your <code>Stack</code> class should have a <code>peek</code> method.'');'
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- text: Your <code>Stack</code> class should have a <code>isEmpty</code> method.
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testString: 'assert((function(){var test = new Stack(); return (typeof test.isEmpty === ''function'')}()), ''Your <code>Stack</code> class should have a <code>isEmpty</code> method.'');'
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- text: Your <code>Stack</code> class should have a <code>clear</code> method.
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testString: 'assert((function(){var test = new Stack(); return (typeof test.clear === ''function'')}()), ''Your <code>Stack</code> class should have a <code>clear</code> method.'');'
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- text: The <code>peek</code> method should return the top element of the stack
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testString: 'assert((function(){var test = new Stack(); test.push(''CS50''); return (test.peek() === ''CS50'')}()), ''The <code>peek</code> method should return the top element of the stack'');'
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- text: The <code>pop</code> method should remove and return the top element of the stack
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testString: 'assert((function(){var test = new Stack(); test.push(''CS50''); return (test.pop() === ''CS50'');}()), ''The <code>pop</code> method should remove and return the top element of the stack'');'
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- text: The <code>isEmpty</code> method should return true if a stack does not contain any elements
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testString: 'assert((function(){var test = new Stack(); return test.isEmpty()}()), ''The <code>isEmpty</code> method should return true if a stack does not contain any elements'');'
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- text: The <code>clear</code> method should remove all element from the stack
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testString: 'assert((function(){var test = new Stack(); test.push(''CS50''); test.clear(); return (test.isEmpty())}()), ''The <code>clear</code> method should remove all element from the stack'');'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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function Stack() {
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var collection = [];
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this.print = function() {
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console.log(collection);
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};
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// Only change code below this line
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// Only change code above this line
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}
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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