/phase-1-array-find-method-lab

Primary LanguageJavaScriptOtherNOASSERTION

Using the Array Find Method

Learning Goals

  • Practice using find() to isolate a specific result

Introduction

We have learned that the indexOf() and find() methods can be used to locate an element in an array, and that they return the first element for which the condition is met. (If you instead want a list of all elements that meet a condition, you would use Array.prototype.filter() instead. We'll learn about filter() in the next lesson.)

We've also learned that the find() method takes a callback function as its argument. This is a common pattern for the Array methods we'll be learning about in this section — in fact, indexOf() is the only one that doesn't take a callback function as an argument. find() is one of two Array methods that expects the callback function to return either true or false (filter() is the other one).

In this lab, we'll practice using the find() method.

Practice Using find() to Isolate a Specific Result

Let's create a function that uses the method find() to single out a specific result in game record data for the Denver Broncos football team. We want to find out if, at any point in the team's existence, they've had a win in the Superbowl. Our data looks like this:

const record = [
  { year: "2015", result: "W"},
  { year: "2014", result: "N/A"},
  { year: "2013", result: "L"},
  //...
]

Write a function called superbowlWin() in index.js:

  • The function should receive 1 argument, an Array of JavaScript Objects
  • Each object has two properties: year and result
  • It should use find() to test each Object to see if the result is "W" — a win!
  • It should return the year when the win occurred (if it occurred at all!)
  • If no win is found, it should return, sadly, undefined

Remember the workflow:

  1. Install the dependencies using npm install.
  2. Run the tests using npm test.
  3. Read the errors; vocalize what they're asking you to do.
  4. Write code; repeat steps 2 and 3 often until a test passes.
  5. Repeat as needed for the remaining tests.

After you have all the tests passing, remember to commit and push your changes up to GitHub, then submit your work to Canvas using CodeGrade.

Conclusion

Array.prototype.find() is a built-in function in JavaScript which is used to get the value of the first element in the array that satisfies the provided condition. With this, you can quickly check all the elements of the array and return the first match.

Resources