Avatar of freddie2025

freddie2025's solution

to Resistor Color Duo in the JavaScript Track

Published at Mar 11 2020 · 0 comments
Instructions
Test suite
Solution

If you want to build something using a Raspberry Pi, you'll probably use resistors. For this exercise, you need to know two things about them:

  • Each resistor has a resistance value.
  • Resistors are small - so small in fact that if you printed the resistance value on them, it would be hard to read.

To get around this problem, manufacturers print color-coded bands onto the resistors to denote their resistance values. Each band has a position and a numeric value. For example, if they printed a brown band (value 1) followed by a green band (value 5), it would translate to the number 15.

In this exercise you are going to create a helpful program so that you don't have to remember the values of the bands. The program will take color names as input and output a two digit number, even if the input is more than two colors!

The colors are mapped to the numbers from 0 to 9 in the sequence: Black - Brown - Red - Orange - Yellow - Green - Blue - Violet - Grey - White

From the example above: brown-green should return 15 brown-green-violet should return 15 too, ignoring the third color.

Setup

Go through the setup instructions for Javascript to install the necessary dependencies:

https://exercism.io/tracks/javascript/installation

Requirements

Install assignment dependencies:

$ npm install

Making the test suite pass

Execute the tests with:

$ npm test

In the test suites all tests but the first have been skipped.

Once you get a test passing, you can enable the next one by changing xtest to test.

Source

Maud de Vries, Erik Schierboom https://github.com/exercism/problem-specifications/issues/1464

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

resistor-color-duo.spec.js

import { decodedValue } from './resistor-color-duo.js';

describe('Resistor Colors', () => {
  test('Brown and black', () => {
    expect(decodedValue(['brown', 'black'])).toEqual(10);
  });

  xtest('Blue and grey', () => {
    expect(decodedValue(['blue', 'grey'])).toEqual(68);
  });

  xtest('Yellow and violet', () => {
    expect(decodedValue(['yellow', 'violet'])).toEqual(47);
  });

  xtest('Orange and orange', () => {
    expect(decodedValue(['orange', 'orange'])).toEqual(33);
  });

  xtest('Ignore additional colors', () => {
    expect(decodedValue(['green', 'brown', 'orange'])).toEqual(51);
  })
});
//
// This is only a SKELETON file for the 'Resistor Color Duo' exercise. It's been provided as a
// convenience to get you started writing code faster.
//

export const decodedValue = (selectedColors) => {
  return parseInt(COLORS.indexOf(selectedColors[0]) + '' + COLORS.indexOf(selectedColors[1]));
};

const COLORS = [
  "black",
  "brown",
  "red",
  "orange",
  "yellow",
  "green",
  "blue",
  "violet",
  "grey",
  "white"
];

Community comments

Find this solution interesting? Ask the author a question to learn more.

What can you learn from this solution?

A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

  • What compromises have been made?
  • Are there new concepts here that you could read more about to improve your understanding?