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id	title	challengeType
587d7b7c367417b2b2512b1a	Access Property Names with Bracket Notation	1

Description

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 foods object is being used in a program for a supermarket cash register. We have some function that sets the selectedFood and we want to check our foods object for the presence of that food. This might look like:

let selectedFood = getCurrentFood(scannedItem);
let inventory = foods[selectedFood];

This code will evaluate the value stored in the selectedFood variable and return the value of that key in the foods object, or undefined 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.

Instructions

We've defined a function, checkInventory, which receives a scanned item as an argument. Return the current value of the scannedItem key in the foods object. You can assume that only valid keys will be provided as an argument to checkInventory.

Tests

tests:
  - text: <code>checkInventory</code> is a function
    testString: assert.strictEqual(typeof checkInventory, 'function', '<code>checkInventory</code> is a function');
  - 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>'
    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>'');'
  - text: <code>checkInventory("apples")</code> should return <code>25</code>
    testString: assert.strictEqual(checkInventory('apples'), 25, '<code>checkInventory("apples")</code> should return <code>25</code>');
  - text: <code>checkInventory("bananas")</code> should return <code>13</code>
    testString: assert.strictEqual(checkInventory('bananas'), 13, '<code>checkInventory("bananas")</code> should return <code>13</code>');
  - text: <code>checkInventory("strawberries")</code> should return <code>27</code>
    testString: assert.strictEqual(checkInventory('strawberries'), 27, '<code>checkInventory("strawberries")</code> should return <code>27</code>');

Challenge Seed

let foods = {
  apples: 25,
  oranges: 32,
  plums: 28,
  bananas: 13,
  grapes: 35,
  strawberries: 27
};
// do not change code above this line

function checkInventory(scannedItem) {
  // change code below this line

}

// change code below this line to test different cases:
console.log(checkInventory("apples"));

Solution

// solution required

3.3 KiB Raw Blame History