/fewpjs-iterators-fndcl-fnexpr-find-lab-dc-web-012720

Primary LanguageJavaScriptOtherNOASSERTION

Iterator Drill: Find

Learning Goals

  • Demonstrate find()
  • Use find() to isolate a specific result

Introduction

In any programming language, you'll perform operations on arrays. Looking in an Array for a sub string or set of characters is a common task. Sometimes you need to look for a specific item in the array, and return it. Given a string or array you can iterate over its elements and perform actions. ES6 introduced a few new Array methods--one of them being find().

Demonstrate find()

The find function behaves similar to others in JavaScript (like filter) that want a truthy/falsey result. find returns the first element for which the function returns true, a single element.

[1,3,5,6,8].find(function(e) { return e % 2 === 0 })

Note: You could have multiple matches, but find returns only the first element. This could lead to some bugs if you're not careful.

let roommates = ["jess", "winston", "winston", "nick"];

roommates.find( function(s) { return s === "winston" })
//=> winston

roommates.filter(function(s) { return s === "winston" })
//=> [winston, winston]

Use 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 football team Kansas City Chiefs. 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: "2018", result: "L"},
  {year: "2017", result: "W"},
  {year: "2016", result: "N/A"}
  //...
]

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

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

Run the tests using learn.

Conclusion

Array.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 returns the first match.

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