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n0mn0m's solution

to RNA Transcription in the TypeScript Track

Published at Feb 16 2021 · 0 comments
Instructions
Test suite
Solution

Note:

This exercise has changed since this solution was written.

Given a DNA strand, return its RNA complement (per RNA transcription).

Both DNA and RNA strands are a sequence of nucleotides.

The four nucleotides found in DNA are adenine (A), cytosine (C), guanine (G) and thymine (T).

The four nucleotides found in RNA are adenine (A), cytosine (C), guanine (G) and uracil (U).

Given a DNA strand, its transcribed RNA strand is formed by replacing each nucleotide with its complement:

  • G -> C
  • C -> G
  • T -> A
  • A -> U

Setup

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

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

Requirements

Install assignment dependencies:

$ yarn install

Making the test suite pass

Execute the tests with:

$ yarn 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 xit to it.

Source

Hyperphysics http://hyperphysics.phy-astr.gsu.edu/hbase/Organic/transcription.html

Submitting Incomplete Solutions

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

rna-transcription.test.ts

import Transcriptor from './rna-transcription'

describe('Transcriptor', () => {
  const transcriptor = new Transcriptor()

  it('transcribes cytosine to guanine', () => {
    expect(transcriptor.toRna('C')).toEqual('G')
  })

  xit('transcribes guanine to cytosine', () => {
    expect(transcriptor.toRna('G')).toEqual('C')
  })

  xit('transcribes adenine to uracil', () => {
    expect(transcriptor.toRna('A')).toEqual('U')
  })

  xit('transcribes thymine to adenine', () => {
    expect(transcriptor.toRna('T')).toEqual('A')
  })

  xit('transcribes all dna nucleotides to their rna complements', () => {
    expect(transcriptor.toRna('ACGTGGTCTTAA'))
      .toEqual('UGCACCAGAAUU')
  })

  xit('correctly handles invalid input', () => {
    expect(() => transcriptor.toRna('U')).toThrowError(
      'Invalid input DNA.'
    )
  })

  xit('correctly handles completely invalid input', () => {
    expect(() => transcriptor.toRna('XXX')).toThrowError(
      'Invalid input DNA.'
    )
  })

  xit('correctly handles partially invalid input', () => {
    expect(() => transcriptor.toRna('ACGTXXXCTTAA')).toThrowError(
      'Invalid input DNA.'
    )
  })

})
class Transcriptor {
    private strandMap : {[key:string]:string} = {
        G : 'C',
        C : 'G',
        T : 'A',
        A : 'U'
    };

    toRna( strand:string ) :string{
        return strand
            .split("")
            .map(item => {
                const mapElement = this.strandMap[item];

                if (!mapElement) {
                    throw new Error("Invalid input DNA.");
                }

                return mapElement;
            })
            .join("");
    }
}

export default Transcriptor

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