Soft Play

Setup

Fork this repository to your GitHub account
Clone your forked repository to your machine
Change directory into the project.
Install the project dependencies

npm ci

Requirements

You need to write a program that maintains a count of both the number of children and adults inside a soft player center. Inside the src/soft-play.js file, you should add the following functions:

function enter(numAdults, numChildren)

This function is used to register adults and children entering the soft play center. The function should check for the following conditions:

Every child entering the soft play center is accompanied by at least 1 adult.

If any of these checks fail, the function should return false. Otherwise, the function should return true and numAdults and numChildren should be added to the current totals.

function leave(numAdults, numChildren)

This function is used to register adults and children leaving the soft play center. The function should check for the following conditions:

A child is not attempting to leave without an adult
The number of adults and children left inside the center will not cause there to be more children than adults (there must be at least 1 adult for 1 child inside the center at all times)
Every child leaving the soft play center is accompanied by at least 1 adult.
The number of adults and children attempting to leave is not greater than the number currently inside the center

If any of these checks fail, function should return false. Otherwise, the function should return true and numAdults and numChildren should be deducted from the current totals.

function occupancy()

This function should return an object with two keys - adults should contain the number of adults currently inside the soft play center and children the number of children. For example:

{
  adults: 4,
  children: 3
}

Tips

Remember functions also have access to variables defined in their enclosing scope. For example both of the functions below update the same counter variable:

let counter = 0

function incrementCounter() {
  counter++
}

function decrementCounter() {
  counter--
}

Example

The REPL extract below illustrates the expected behavior of the functions.

//counts start at 0
> occupancy()
{ adults: 0, children: 0 }

//2 adults and 1 child enter
> enter(2, 1)
true

//counts are updated
> occupancy()
{ adults: 2, children: 1 }  

//1 adult leaves
> leave(1, 0)
true

//Only 1 adult and 1 child remain
> occupancy()
{ adults: 1, children: 1 }

//a child attempts to enter on their own, enter returns false
> enter(0,1)  
false

//counts stay the same
> occupancy()
{ adults: 1, children: 1 }

//the last adult attempts to leave so false is returned (as child would be on their own in soft play)
> leave(1,0)
false

//counts stay the same
> occupancy()
{ adults: 1, children: 1 }

//the last child and adult leave together
> leave(1,1)
true

//both counts are now 0
> occupancy()
{ adults: 0, children: 0 }

Testing

A suite of tests has already been created for your functions inside spec/soft-play.spec.js. You should not need to modify this file. You can run the tests using:

$ npm test # runs all standard tests
$ npm run test-extensions # runs all extension tests
$ npx eslint src # runs the linter
$ npx jasmine path/to/spec/file # runs specific files

You can focus on passing one test at a time by implementing your functions step by step. When all the tests pass, you know your functions are complete. You can look at the test cases in the spec/soft-play.spec.js file, but you should not change any of the code.

Extension

Once you have finished the basic functions, you can extend the exercise to include an additional function:

total()

This function should return an object with the same structure as occupancy, but the values should be the all-time totals showing how many adults and children have entered the soft play center.

Reflection

Once you have completed the exercise, take a moment to ask yourself the following questions and consider how you could implement changes to your code to support these:

The functions you have created only consider a single soft play center - what if we wanted to keep track of multiple soft play centers at the same time?
If we do keep track of multiple soft play centers, imagine we also want to have different rules for different centers. For example, perhaps some centers a child must be accompanied by at least 2 adults. How would you implement this?

shurtugal77/js-softplay