Closures Lab

Objectives

  • Use closures to customize functions
  • Use closures as a mechanism of encapsulations

Instructions

In the lab that follows, practice using closures to construct functions that have reference to variables that the execution scope does not.

Create the following functions:

  • produceDrivingRange() - Calculates whether a given trip is within range. For example, produceDrivingRange(10) returns a function that will take two strings as arguments and returns a message stating whether the trip is in range. If foo = produceDrivingRange(10), then foo('12th', '15th') would return "within range by 7" and foo('12th', '30th') would return "8 blocks out of range". We recommend referencing the test/indexTest.js for more details.

  • produceTipCalculator() - Returns a function that then calculates a tip. For example, produceTipCalculator(.10) returns a function that calculates ten percent tip on a fare. produceTipCalculator(.20) returns a function that calculates twenty percent tip on a fare.

  • createDriver is a function that returns a Driver class. The class has reference to a driverId that is incremented each time a new driver is created. The rest of the code base does not have access to driverId.

The functions should make use of closures to achieve the specified goals.

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