79d9012432
* fix(curriculum): tests quotes * fix(curriculum): fill seed-teardown * fix(curriculum): fix tests and remove unneeded seed-teardown
77 lines
3.3 KiB
Markdown
77 lines
3.3 KiB
Markdown
---
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id: 587d7b7c367417b2b2512b1a
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title: Access Property Names with Bracket Notation
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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 first object challenge we mentioned the use of bracket notation as a way to access property values using the evaluation of a variable. For instance, imagine that our <code>foods</code> object is being used in a program for a supermarket cash register. We have some function that sets the <code>selectedFood</code> and we want to check our <code>foods</code> object for the presence of that food. This might look like:
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<blockquote>let selectedFood = getCurrentFood(scannedItem);<br>let inventory = foods[selectedFood];</blockquote>
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This code will evaluate the value stored in the <code>selectedFood</code> variable and return the value of that key in the <code>foods</code> object, or <code>undefined</code> if it is not present. Bracket notation is very useful because sometimes object properties are not known before runtime or we need to access them in a more dynamic way.
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</section>
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## Instructions
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<section id='instructions'>
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We've defined a function, <code>checkInventory</code>, which receives a scanned item as an argument. Return the current value of the <code>scannedItem</code> key in the <code>foods</code> object. You can assume that only valid keys will be provided as an argument to <code>checkInventory</code>.
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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: <code>checkInventory</code> is a function
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testString: assert.strictEqual(typeof checkInventory, 'function', '<code>checkInventory</code> is a function');
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- text: 'The <code>foods</code> object should have only the following key-value pairs: <code>apples: 25</code>, <code>oranges: 32</code>, <code>plums: 28</code>, <code>bananas: 13</code>, <code>grapes: 35</code>, <code>strawberries: 27</code>'
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testString: 'assert.deepEqual(foods, {apples: 25, oranges: 32, plums: 28, bananas: 13, grapes: 35, strawberries: 27}, ''The <code>foods</code> object should have only the following key-value pairs: <code>apples: 25</code>, <code>oranges: 32</code>, <code>plums: 28</code>, <code>bananas: 13</code>, <code>grapes: 35</code>, <code>strawberries: 27</code>'');'
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- text: <code>checkInventory("apples")</code> should return <code>25</code>
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testString: assert.strictEqual(checkInventory('apples'), 25, '<code>checkInventory("apples")</code> should return <code>25</code>');
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- text: <code>checkInventory("bananas")</code> should return <code>13</code>
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testString: assert.strictEqual(checkInventory('bananas'), 13, '<code>checkInventory("bananas")</code> should return <code>13</code>');
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- text: <code>checkInventory("strawberries")</code> should return <code>27</code>
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testString: assert.strictEqual(checkInventory('strawberries'), 27, '<code>checkInventory("strawberries")</code> should return <code>27</code>');
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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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let foods = {
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apples: 25,
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oranges: 32,
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plums: 28,
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bananas: 13,
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grapes: 35,
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strawberries: 27
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};
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// do not change code above this line
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function checkInventory(scannedItem) {
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// change code below this line
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}
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// change code below this line to test different cases:
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console.log(checkInventory("apples"));
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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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