firstprayer.github.com/how-long-is.html at master · firstprayer/firstprayer.github.com · GitHub

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<!Doctype html>
<html>
<head>
	<meta charset="UTF-8">
<meta name="description" content="A tool for visualizing how long an object will be given the length description">
<meta name="keywords" content="Ruler,length,long,visualization,unit converter,unit conversion">
<meta name="author" content="Taiyuan Zhang">

	<style type="text/css">
		#display {
			height: 5px;
			background: #000;
			width: 0;
		}
	</style>
</head>

<body>
	<div>Descibe the length (10 cm, 2.4 inches, 2 feet 7 inches, 6 inches 1/4 inches, etc)</div>
	<div>
		<input type='text' id='input' />
		<span id='error' style='color:red'></span>
	</div>
	<div style='margin-top: 10px'>
		<div id='display'></div>
	</div>

<script   src="https://code.jquery.com/jquery-2.2.4.min.js"   integrity="sha256-BbhdlvQf/xTY9gja0Dq3HiwQF8LaCRTXxZKRutelT44="   crossorigin="anonymous"></script>

<script type="text/javascript">
(function($, window) {

var StandardMeasure = 'm';

var Unit = function (value) { this.value = value; };
Unit.prototype.toStandard = function () {
	throw new Error('Not implemented');
}
var makeUnitClass = function (scaleFactor) {
	var newClass = function () { Unit.apply(this, arguments); };
	newClass.prototype.toStandard = function () { return this.value * scaleFactor; };
	return newClass;
}
var Meter = makeUnitClass(1);
var Centimeter = makeUnitClass(0.01);
var Yard = makeUnitClass(0.9144);
var Foot = makeUnitClass(0.3048);
var Inch = makeUnitClass(0.0254);

var createUnit = function(staticClass, num) { return new staticClass(num); }

function updateLength(length, $displayDom) {
	$displayDom.width(length * 100 + 'cm');
}

var INCORRECT_FORMAT_ERROR = 'Incorrect format',
	INVALID_UNIT_ERROR_PREFIX = 'Invalid unit: ',
	MUST_BE_POSITIVE_NUMBER = 'Number must be positive: ';

function parseUnit(stringValue) {
	stringValue = $.trim(stringValue);
	var data = stringValue.split(' ');
	if (data.length % 2 !== 0 || data.length < 2) {
		throw new Error(INCORRECT_FORMAT_ERROR);
	}

	var cnt = data.length / 2;
	var units = [];
	for (var i = 0; i < cnt; i++) {
		var numString = data[i * 2],
			unitName = data[i * 2 + 1];

		var num = null;
		// Maybe in the stye of n/m.
		var parts = numString.split('/');
		var num = parseFloat(numString);
		if (parts.length === 2) {
			var n = parseFloat(parts[0]),
				m = parseFloat(parts[1]);
			num = n / m;
		}

		if (! (num > 0)) {
			num = parseFloat(numString);
		}

		if (! (num > 0)) {
			throw new Error(MUST_BE_POSITIVE_NUMBER + numString);
		}

		var unitMatch = function (unitCandidates) {
			if (unitCandidates.indexOf(unitName) >= 0) {
				return true;
			} else {
				return false;
			}
		}

		units.push((function() {
			if (unitMatch(['m', 'meter', 'meters'])) { return new Meter(num); }
			if (unitMatch(['cm', 'centimeter', 'centimeters'])) { return new Centimeter(num); }
			if (unitMatch(['f', 'foot', 'feet', 'foots', 'feets'])) { return new Foot(num); }
			if (unitMatch(['y', 'yard', 'yards'])) { return new Yard(num); }
			if (unitMatch(['inch', 'inches'])) { return new Inch(num); }

			throw new Error(INVALID_UNIT_ERROR_PREFIX + unitName);
		}()));
	}
	return units;
}

function getLength(units) {
	var val = 0;
	for (var i = 0; i < units.length; i++) {
		val += units[i].toStandard();
	}
	return val;
}

var $inputDom = $('#input'),
	$displayDom = $('#display'),
	$errorMsgDom = $('#error');

$inputDom.on('keyup', function(e) {
	var stringValue = $(this).val();
	var units = null;
	try {
		units = parseUnit(stringValue);
	} catch (err) {
		$errorMsgDom.html(err.message);
		$displayDom.width(0);
		return;
	}
	$errorMsgDom.html('');
	updateLength(getLength(units), $displayDom);
});

// Inline test cases.
function assertEq(a, b) {
	if (Math.abs(a - b) > 0.0000001) {
		$errorMsgDom.html(a + ' != ' + b);
	}
}
assertEq(getLength(parseUnit('10 cm')), '0.1');
assertEq(getLength(parseUnit('11.5 cm 10 cm')), '0.215');
assertEq(getLength(parseUnit('1/4 m 10 cm')), '0.35');

})(jQuery, window);
</script>

</body>

</html>