freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/rosetta-code/generate-lower-case-ascii-alphabet.md

title	id	challengeType	forumTopicId
Generate lower case ASCII alphabet	5a23c84252665b21eecc7e7a	5	302274

Description

Write a function to generate an array of lower case ASCII characters for a given range. For example, given the range ['a', 'd'], the function should return ['a', 'b', 'c', 'd'].

Instructions

Tests

tests:
  - text: <code>lascii</code> should be a function.
    testString: assert(typeof lascii=='function');
  - text: <code>lascii("a","d")</code> should return an array.
    testString: assert(Array.isArray(lascii('a','d')));
  - text: "<code>lascii('a','d')</code> should return <code>[ 'a', 'b', 'c', 'd' ]</code>."
    testString: assert.deepEqual(lascii("a","d"),results[0]);
  - text: <code>lascii('c','i')</code> should return <code>[ 'c', 'd', 'e', 'f', 'g', 'h', 'i' ]</code>.
    testString: assert.deepEqual(lascii("c","i"),results[1]);
  - text: <code>lascii('m','q')</code> should return <code>[ 'm', 'n', 'o', 'p', 'q' ]</code>.
    testString: assert.deepEqual(lascii("m","q"),results[2]);
  - text: <code>lascii('k','n')</code> should return <code>[ 'k', 'l', 'm', 'n' ]</code>.
    testString: assert.deepEqual(lascii("k","n"),results[3]);
  - text: <code>lascii('t','z')</code> should return <code>[ 't', 'u', 'v', 'w', 'x', 'y', 'z' ]</code>.
    testString: assert.deepEqual(lascii("t","z"),results[4]);

Challenge Seed

function lascii(cFrom, cTo) {

}

After Test

let results=[
  [ 'a', 'b', 'c', 'd' ],
  [ 'c', 'd', 'e', 'f', 'g', 'h', 'i' ],
  [ 'm', 'n', 'o', 'p', 'q' ],
  [ 'k', 'l', 'm', 'n' ],
  [ 't', 'u', 'v', 'w', 'x', 'y', 'z' ]
]

Solution

function lascii(cFrom, cTo) {

  function cRange(cFrom, cTo) {
    var iStart = cFrom.charCodeAt(0);

    return Array.apply(
      null, Array(cTo.charCodeAt(0) - iStart + 1)
    ).map(function (_, i) {

      return String.fromCharCode(iStart + i);

    });
  }

  return cRange(cFrom, cTo);

}