Source

Source: Adapted from Jeffrey Hu, Python programming exercises, Question 13

Description

Count letters and digits.

Given a string, return an array containing counts of letters and digits, in the format [ls, ds].

1

'hello world! 123' ⟹ [10, 3]

My solution

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const isAlpha   = s => /^[a-zA-Z]+$/.test(s);

const isNumeric = s => /^[0-9]+$/.test(s);

const countLd = s => [
    [...s].filter(isAlpha).length,
    [...s].filter(isNumeric).length
];


module.exports = {countLd};

Tests

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const assert = require('assert')
    , countLd = require('./countLd.js').countLd;

describe('countLd()', function() {
    it('should return the correct counts', function() {
        const s = 'hello world! 123';
        assert.deepEqual(countLd(s), [10, 3]);
    });
});