97 lines
3.0 KiB
Markdown
97 lines
3.0 KiB
Markdown
---
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title: Comma quibbling
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id: 596e414344c3b2872167f0fe
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challengeType: 5
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forumTopicId: 302234
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---
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## Description
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<section id='description'>
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Comma quibbling is a task originally set by Eric Lippert in his <a href="https://blogs.msdn.com/b/ericlippert/archive/2009/04/15/comma-quibbling.aspx" target="_blank">blog</a>.
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</section>
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## Instructions
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<section id='instructions'>
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Write a function to generate a string output which is the concatenation of input words from a list/sequence where:
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<ol>
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<li>An input of no words produces the output string of just the two brace characters (<code>"{}"</code>)</li>
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<li>An input of just one word, e.g. <code>["ABC"]</code>, produces the output string of the word inside the two braces, e.g. <code>"{ABC}"</code></li>
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<li>An input of two words, e.g. <code>["ABC", "DEF"]</code>, produces the output string of the two words inside the two braces with the words separated by the string <code>" and "</code>, e.g. <code>"{ABC and DEF}"</code></li>
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<li>An input of three or more words, e.g. <code>["ABC", "DEF", "G", "H"]</code>, produces the output string of all but the last word separated by <code>", "</code> with the last word separated by <code>" and "</code> and all within braces; e.g. <code>"{ABC, DEF, G and H}"</code></li>
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</ol>
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Test your function with the following series of inputs showing your output here on this page:
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<ul>
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<li>[] # (No input words).</li>
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<li>["ABC"]</li>
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<li>["ABC", "DEF"]</li>
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<li>["ABC", "DEF", "G", "H"]</li>
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</ul>
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<strong>Note:</strong> Assume words are non-empty strings of uppercase characters for this task.
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: <code>quibble</code> should be a function.
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testString: assert(typeof quibble === 'function');
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- text: <code>quibble(["ABC"])</code> should return a string.
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testString: assert(typeof quibble(["ABC"]) === 'string');
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- text: <code>quibble([])</code> should return "{}".
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testString: assert.equal(quibble(testCases[0]), results[0]);
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- text: <code>quibble(["ABC"])</code> should return "{ABC}".
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testString: assert.equal(quibble(testCases[1]), results[1]);
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- text: <code>quibble(["ABC", "DEF"])</code> should return "{ABC and DEF}".
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testString: assert.equal(quibble(testCases[2]), results[2]);
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- text: <code>quibble(["ABC", "DEF", "G", "H"])</code> should return "{ABC,DEF,G and H}".
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testString: assert.equal(quibble(testCases[3]), results[3]);
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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function quibble(words) {
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return true;
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}
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```
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</div>
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### After Test
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<div id='js-teardown'>
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```js
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const testCases = [[], ["ABC"], ["ABC", "DEF"], ["ABC", "DEF", "G", "H"]];
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const results = ["{}", "{ABC}", "{ABC and DEF}", "{ABC,DEF,G and H}"];
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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function quibble(words) {
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return "{" +
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words.slice(0, words.length - 1).join(",") +
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(words.length > 1 ? " and " : "") +
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(words[words.length - 1] || '') +
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"}";
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}
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```
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</section>
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