Functions Lab

Objectives

1. Practice writing functions
2. Explain calling functions from within other functions
3. Practice basics of control flow and return statements

Introduction

Scuber has gained some traction among moms and dads in New York City. It has also received a few requests.

First, Scuber's executives want to ensure that Scuber's headquarters is near its customers. They ask you to write a function that takes in a pickup location for a passenger, and returns the number of blocks from it's headquarters on 42nd street. This can be used for another function that translates the number of blocks from headquarters to the distance in feet.

Second, customers want Scuber to calculate the number of feet travelled based on the distance. Write a function called distanceTravelledInFeet that takes in the beginning and destination blocks and returns the number of feet travelled. Each block in Manhattan is 264 feet long. For example distanceTravelledInFeet(34, 38) representing 34th St to 38th St, returns 1056 ((38-34)*264). You can assume that we are only calculating distance uptown/downtown, not from river to river.

Instructions

If you run learn you will see the tests are currently breaking; you will need to write these functions from scratch, and test them as you go to get them working. It's easier to understand and solve the problem if you look through the tests, which are located in test/indexTest.js. After the word describe, you will see the name of the function that the test is testing, for example the first function tested is distanceFromHqInBlocks. Then, after the word it, you can see the specifications of the function. The test literally calls the function that you write in index.js. So the first test will call your declared function distanceFromHqInBlocks and pass through an argument of 43.

• distanceFromHqInBlocks: Returns the number of blocks from Scuber's headquarters to the pickup location.

• distanceFromHqInFeet: Returns the number of feet from Scuber's headquarters to the pickup location. Note that you can use your distanceFromHqInBlocks function to help return the correct value here. Here is an example of how to do this:

function distanceFromHqInBlocks (someValue) {
  //returns the number of blocks given a value
}

function distanceFromHqInFeet (someValue) {
  distanceFromHqInBlocks(someValue);
  // calls distanceFromHqInBlocks from inside the distanceFromHqInFeet function, passing the argument from distanceFromHqInFeet into distanceFromHqInBlocks
  //the return value of distanceFromHqInBlocks can then be used to calculate feet
}

• distanceTravelledInFeet: Calculates the number of feet a passenger travels given a starting block and an ending block - it only calculates distance North and South (uptown/downtown). It uses the knowledge that a block is 264 feet long.

• calculatesFarePrice: Given the same starting and ending block as the previous test (hint hint), return the fare for the customer. The first four hundred feet are free. For a distance between 400 and 2000 feet, the price is 2 cents per foot (not including 400, which are free!). Then Scuber charges a flat fare for a distance over 2000 feet and under 2500 feet. Finally, Scuber does not allow any rides over 2500 feet - the function returns 'cannot travel that far' if a ride over 2500 feet is requested.

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