sortClothingSizes.js

/**
 * JS utility function to sort an array of clothing sizes (["M", "S", "XL", "XXS"])
 * by size and not alphabetically.
 * 
 * Usage:
 
 ```
 clothingSizesSort(["S", "M", "XL"]) // should === ["XXS", "S", "M", "XL")
 ```
 
 */

/*************
 * FUNCTIONS *
 *************/

/**
 * sort an array of sizes
 */
function clothingSizesSort(sizesRaw) {
	// pair sizes with their numerical values
	const sizesWithNumValue = sizesRaw.map(size => {
		return {
			raw: size,
			num: numValue(size)
		};
	});

	// and sort them ascending
	const sizesSortedByNumValue = sizesWithNumValue.sort(
		(a, b) => a.num - b.num
	);

	return sizesSortedByNumValue.map(el => el.raw);
}

/**
 * parse a size independent from type
 */
function numValue(raw) {
	const num = parseInt(raw);
	if (typeof raw === "string") {
		// raw is numerical string, e.g "45"
		if (raw !== num.toString()) {
			return sizeStrValue(raw);
		}
	}
	return num;
}

/**
 * convert a size string into a number value for sorting.
 * XS = 0.1, S = 1, M = 10, L = 100, XL = 10000 and so forth
 */
function sizeStrValue(sizeStr) {
	sizeStr = sizeStr.toLowerCase();

	// special case SM = 5
	if (sizeStr === "sm") {
		return 5;
	}

	const sizePcs = sizeStr.split("");
	const sizeName = sizePcs.pop();
	let multiplier = Math.pow(10, sizePcs.length);
	let sizeValue = 0;

	switch (sizeName) {
		case "s":
			sizeValue = 1;
			// [...X]S inverts the multiplier
			multiplier = 1 / multiplier;
			break;
		case "m":
			sizeValue = 10;
			break;
		case "l":
			sizeValue = 100;
			break;
	}

	return sizeValue * multiplier;
}

/*************
 *  "TESTS"  *
 *************/

const tests = [
	{
		in: ["45", "42", "38", "46"],
		expect: ["38", "42", "45", "46"]
	},
	{
		in: [45, 42, 38, 46],
		expect: [38, 42, 45, 46]
	},
	,
	{
		in: ["s", "xxl", "m"],
		expect: ["s", "m", "xxl"]
	},
	{
		in: ["m", "s", "xl", "xxl", "xs", "xxs", "sm", "xxxxxxl", "xxxxxxxxxs"],
		expect: [
			"xxxxxxxxxs",
			"xxs",
			"xs",
			"s",
			"sm",
			"m",
			"xl",
			"xxl",
			"xxxxxxl"
		]
	},
	{
		in: ["foo"],
		expect: ["foo"]
	},
	{
		in: [],
		expect: []
	}
];

tests.forEach(test => {
	const result = clothingSizesSort(test.in);
	const equals = JSON.stringify(result) === JSON.stringify(test.expect);

	if (equals) {
		console.log("- ok -");
	} else {
		console.log("- fail -");
		console.log(result);
		console.log("- expected -");
		console.log(test.expect);
	}
});