isValidVin

isValidVin.test.ts

import isValidVin from './isValidVin.ts';

describe('isValidVin', () => {
  it('should return false for an invalid 16 digit VIN', () => {
    const vin = 'JHLRM4H70CC01839';

    expect(isValidVin(vin)).toBe(false);
  });

  it('should return false for an invalid 18 digit VIN', () => {
    const vin = 'JHLRM4H70CC01839AB';

    expect(isValidVin(vin)).toBe(false);
  });

  it('should return false for an invalid 17 digit VIN with `i`', () => {
    const vin = 'JHLRM4H70CC01839i';

    expect(isValidVin(vin)).toBe(false);
  });

  it('should return false for an invalid 17 digit VIN with `I`', () => {
    const vin = 'JHLRM4H70CC01839I';

    expect(isValidVin(vin)).toBe(false);
  });

  it('should return false for an invalid 17 digit VIN with `o`', () => {
    const vin = 'JHLRM4H70CC01839o';

    expect(isValidVin(vin)).toBe(false);
  });

  it('should return false for an invalid 17 digit VIN with `O`', () => {
    const vin = 'JHLRM4H70CC01839o';

    expect(isValidVin(vin)).toBe(false);
  });

  it('should return false for an invalid 17 digit VIN with `q`', () => {
    const vin = 'JHLRM4H70CC01839o';

    expect(isValidVin(vin)).toBe(false);
  });

  it('should return false for an invalid 17 digit VIN with `Q`', () => {
    const vin = 'JHLRM4H70CC01839o';

    expect(isValidVin(vin)).toBe(false);
  });

  it('should return true for a valid 17 digit VIN in lowercase letters', () => {
    const vin = 'jhlrm4h70cc018394';

    expect(isValidVin(vin)).toBe(true);
  });

  it('should return false for an incorrect check digit with an incorrect 17 digit VIN', () => {
    const vin = 'WVWUK63B82P546818';

    expect(isValidVin(vin)).toBe(false);
  });

  it('should return true for a correct 17 digit VIN', () => {
    const vin = '11111111111111111';

    expect(isValidVin(vin)).toBe(true);
  });
});

isValidVin.ts

/**
 * This function checks is a VIN valid
 */
const isValidVin = (vinCode: string): boolean => {
  const vin: string = vinCode.toLowerCase();

  if (!/^[a-hj-npr-z0-9]{8}[0-9xX][a-hj-npr-z0-9]{8}$/.test(vin)) {
    return false;
  }

  const transliterationTable = {
    '0': 0,
    '1': 1,
    '2': 2,
    '3': 3,
    '4': 4,
    '5': 5,
    '6': 6,
    '7': 7,
    '8': 8,
    '9': 9,
    a: 1,
    b: 2,
    c: 3,
    d: 4,
    e: 5,
    f: 6,
    g: 7,
    h: 8,
    j: 1,
    k: 2,
    l: 3,
    m: 4,
    n: 5,
    p: 7,
    r: 9,
    s: 2,
    t: 3,
    u: 4,
    v: 5,
    w: 6,
    x: 7,
    y: 8,
    z: 9,
  };

  const weightsTable: Array<number> = [
    8, 7, 6, 5, 4, 3, 2, 10, 0, 9, 8, 7, 6, 5, 4, 3, 2,
  ];
  let sum: number = 0;

  for (let i = 0; i < vin.length; i += 1) {
    sum +=
      transliterationTable[vin.charAt(i) as keyof typeof transliterationTable] *
      weightsTable[i];
  }

  const mod: number = sum % 11;

  return mod === 10 ? vin.charAt(8) === 'x' : vin.charAt(8) === mod.toString();
};

export default isValidVin;