matiastorrres/react-js-interview

Interview exercise

Requirement

This is a basic application related to roman numbers. The overall application flow should be the following:

• The user assemble a roman number using the provided UI.
• The system validates the number an indicates if the number is ok or not.
• The user add the number to the current Roman to Integer table.

The exercise will be split in two sections.

1. Implement a function to calculate the integer equivalence of a valid roman number. (30 min)
2. Implement missing UI components to full fill the application requirement. (30 min).

Equivalence calculation

There is an already provided function called romanToIn which should be implemented:

 * This function gets as argument a roman number string for instance
 * XX -> 20
 * XIX -> 19
 * V -> 5
 * VIII -> 8
 * HI -> 0 -- invalid
 * @param romanNumber 
 * @returns integer value of roman number or 0 if its invalid
 */
export const romanToInt = (romanNumber: string): number => {
  if (!isRomanNumberValid(romanNumber)) {
    return 0;
  }
  return 0;
}

• File location: src/utils/roman-conversion.utils.ts
• How to test it: yarn test
• Note that: isRomanNumberValid is already provided and will check that the roman number is valid.

UI Features

The main goal here is to provide a way to:

• visualize the number which is being builded before validate it.
• validate the number before adding to the current number equivalence.
• a valid number might be added to the list.
• at any time the user can clean the current roman number.
• the number list should provide a way to delete current equivalence

For this point we provide a resource mocking an API, and it is expected to be consumed for this challenge.

const numbers: Map<number, string> = new Map();

/**
 * Add a number to list of numbers
 */
export const postNumber = async (nextNum: number, rNumber: string) => {
  if (numbers.has(nextNum)) {
    throw Error('Already there');
  }
  return {
    status: 'ok',
  };
};

export const getNumbers = async () => {
  const numsObject: {intNum: number, romNum: string}[] = [];
  numbers.forEach((romNum,intNum) => {
    numsObject.push({
      intNum,
      romNum
    })
  })
  return numsObject
};

export const removeNumber = async (nextNum: number) => {

  if (!numbers.has(nextNum)) {
    throw Error('This is not the number you are looking for');
  }
  numbers.delete(nextNum);
  return {
    status: 'ok',
  };
};

File location: src/api/number.service.ts