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title	id	challengeType
Comma quibbling	596e414344c3b2872167f0fe	5

Description

Comma quibbling is a task originally set by Eric Lippert in his blog.

Task:

Write a function to generate a string output which is the concatenation of input words from a list/sequence where:

An input of no words produces the output string of just the two brace characters "{}". An input of just one word, e.g. ["ABC"], produces the output string of the word inside the two braces, e.g. "{ABC}". An input of two words, e.g. ["ABC", "DEF"], produces the output string of the two words inside the two braces with the words separated by the string " and ", e.g. "{ABC and DEF}". An input of three or more words, e.g. ["ABC", "DEF", "G", "H"], produces the output string of all but the last word separated by ", " with the last word separated by " and " and all within braces; e.g. "{ABC, DEF, G and H}".

Test your function with the following series of inputs showing your output here on this page:

[] # (No input words). ["ABC"] ["ABC", "DEF"] ["ABC", "DEF", "G", "H"]

Note: Assume words are non-empty strings of uppercase characters for this task.

Instructions

Tests

tests:
  - text: <code>quibble</code> is a function.
    testString: assert(typeof quibble === 'function', '<code>quibble</code> is a function.');
  - text: <code>quibble(["ABC"])</code> should return a string.
    testString: assert(typeof quibble(["ABC"]) === 'string', '<code>quibble(["ABC"])</code> should return a string.');
  - text: <code>quibble([])</code> should return "{}".
    testString: assert.equal(quibble(testCases[0]), results[0], '<code>quibble([])</code> should return "{}".');
  - text: <code>quibble(["ABC"])</code> should return "{ABC}".
    testString: assert.equal(quibble(testCases[1]), results[1], '<code>quibble(["ABC"])</code> should return "{ABC}".');
  - text: <code>quibble(["ABC", "DEF"])</code> should return "{ABC and DEF}".
    testString: assert.equal(quibble(testCases[2]), results[2], '<code>quibble(["ABC", "DEF"])</code> should return "{ABC and DEF}".');
  - text: <code>quibble(["ABC", "DEF", "G", "H"])</code> should return "{ABC,DEF,G and H}".
    testString: assert.equal(quibble(testCases[3]), results[3], '<code>quibble(["ABC", "DEF", "G", "H"])</code> should return "{ABC,DEF,G and H}".');

Challenge Seed

function quibble (words) {
  // Good luck!
  return true;
}

After Test

const testCases = [[], ["ABC"], ["ABC", "DEF"], ["ABC", "DEF", "G", "H"]];
const results = ["{}", "{ABC}", "{ABC and DEF}", "{ABC,DEF,G and H}"];

Solution

function quibble (words) {
  return "{" +
    words.slice(0, words.length - 1).join(",") +
   (words.length > 1 ? " and " : "") +
   (words[words.length - 1] || '') +
  "}";
}

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