Refactoring

Un-refactored code

const URLstore = [];

function makeShort(URL) {

const rndName = Math.random().toString(36).substring(2);

URLstore.push({[rndName]: URL});

return rndName;

}

function getLong(shortURL) {

for (let i = 0; i < URLstore.length; i++) {

  if (URLstore[i].hasOwnProperty(shortURL) !== false) {

    return URLstore[i][shortURL];

}

}

}

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Refactored code

const URLstore = new Map(); // Change this to a Map

function makeShort(URL) {

const rndName = Math.random().toString(36).substring(2); // Place the short URL into the Map as the key with the long URL as the value

URLstore.set(rndName, URL);

return rndName;

}

function getLong(shortURL) { // Leave the function early to avoid an unnecessary else statement

if (URLstore.has(shortURL) === false) {

throw 'Not in URLstore!';

}

return URLstore.get(shortURL); // Get the long URL out of the Map

}

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Pure Functions

Definition: It returns the same result if given the same arguments (it is also referred as deterministic). It does not cause any observable side effects (Examples of observable side effects include modifying a global object or a parameter passed by reference.).