Joshua Alpuerto

May 8, 2019

Hi,

Great Article!

I'm just confused with this instruction on #3. Calculate Employee Gross Pay

Using this base function, create three partial application functions that respectively will calculate the associate, supervisor or admin gross pay when invoked.

I don't think it needs partial application for calculating those 3 roles since the base functions accepts role object already. But it can help to create partial application when computing the grossPay for the total of hourly and overtime.

const getGross = (rate) => (totalHours) => rate * totalHours
const computeGrossSalary = ({
  role = {}, 
  totalHours = 0,
  overtimeTotalHours = 0                        
}) => {
  const { rate: hourlyRate = 0, overtime: overtimeRate = 0 } = role || {}
  const totalHourlySalary = getGross(hourlyRate)
  const totalOvertimeSalary = getGross(overtimeRate)

  return totalHourlySalary(totalHours) +  totalOvertimeSalary(overtimeTotalHours)
}

computeGrossSalary({
  role: { roleId: 3, rate: 12.5, overtime: 18.75 },
  totalHours: 1
})

BTW I know it's bad to assume and should ask the interviewer if not clear. But I assume that the rate is hourly not daily.

Please correct me if am wrong.

Cheers!

Hey Joshua, thank you for the comment and I'm happy you like the article. To quickly answer your question, of course don't 'need' to do it with partials but they are great advantages in using that approach. Let me try to give you a quick example as a basic use case.

Let's say we have a multiplier function that takes two arguments and returns the product. We will use that as our base

function multiply(x, y) {
  return x * y;
}

Now let's say we have the need to calculate often halves, doubles and triples. Partial function application will allow us to create generic, reusable, predictable and intuitive secondary functions as you can see below

const halves = multiply.bind(null, 0.5);
halves(2); // will output 1

const doubles = multiply.bind(null, 2);
doubles(5);  // will output 10

const triples = multiply.bind(null, 3);
triples(27); // will output 81

You get the idea. I will take a closer look at your solution here and give you some feedback on it. But in an interview context it might be best to solve against the specs first then propose a better alternative.

Let me know what you think.

Cheers

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