js小结：JavaScript 代码整洁之道（一）

var yyyymmdstr = moment().format('YYYY/MM/DD');

var yearMonthDay = moment().format('YYYY/MM/DD');

var FIRST_US_PRESIDENT = "George Washington";

const FIRST_US_PRESIDENT = "George Washington";

getUserInfo();getClientData();getCustomerRecord();

getUser();

// 见鬼，525600 是个啥？
for (var i = 0; i < 525600; i++) {
	runCronJob();
}

// 用 `var` 申明为大写的全局变量
var MINUTES_IN_A_YEAR = 525600;for (var i = 0; i < MINUTES_IN_A_YEAR; i++) {
	runCronJob();
}

const cityStateRegex = /^(.+)[,\\s]+(.+?)\s*(\d{5})?$/;
saveCityState(cityStateRegex.match(cityStateRegex)[1], cityStateRegex.match(cityStateRegex)[2]);

const cityStateRegex = /^(.+)[,\\s]+(.+?)\s*(\d{5})?$/;
const match = cityStateRegex.match(cityStateRegex);
const city = match[1];
const state = match[2];saveCityState(city, state);

var locations = ['Austin', 'New York', 'San Francisco'];locations.forEach((l) => {
	doStuff();
	doSomeOtherStuff();
	...
	...
	...
	// 等等，`l` 又是什么？
	dispatch(l);
});

var locations = ['Austin', 'New York', 'San Francisco'];locations.forEach((location) => {
	doStuff();
	doSomeOtherStuff();
	...
	...
	...
	dispatch(location);
 });

var Car = {
	carMake: 'Honda',
	carModel: 'Accord',
	carColor: 'Blue'
};
function paintCar(car) {
	car.carColor = 'Red';
}

var Car = {
	make: 'Honda',
	model: 'Accord',
	color: 'Blue'
};
function paintCar(car) {
	car.color = 'Red';
}

function createMicrobrewery(name) {
	var breweryName;
	if (name) {
		breweryName = name;
	} else {
		breweryName = 'Hipster Brew Co.';
	}
}

function createMicrobrewery(name) {
	var breweryName = name || 'Hipster Brew Co.'
}

function createMenu(title, body, buttonText, cancellable) {
	...
}

var menuConfig = {
	title: 'Foo',
	body: 'Bar',
	buttonText: 'Baz',
	cancellable: true
}
function createMenu(menuConfig) {
	...
}

function emailClients(clients) {
	clients.forEach(client => {
		let clientRecord = database.lookup(client);
		if (clientRecord.isActive()) {
			email(client);
		}
	});
}

function emailClients(clients) {
	clients.forEach(client => {
		emailClientIfNeeded(client);
	});
}
function emailClientIfNeeded(client) {
	if (isClientActive(client)) {
		email(client);
	}
}
function isClientActive(client) {
	let clientRecord = database.lookup(client);
	return clientRecord.isActive();
}

function dateAdd(date, month) {
	// ...
}
let date = new Date();
// 很难从函数名了解到加了什么dateAdd(date, 1);

function dateAddMonth(date, month) {
	// ...
}
let date = new Date();
dateAddMonth(date, 1);

function parseBetterJSAlternative(code) {
	let REGEXES = [
		// ...
	];
	let statements = code.split(' ');
	let tokens;
	REGEXES.forEach((REGEX) => {
		statements.forEach((statement) => {
			// ...
		})
	});
	let ast;
	tokens.forEach((token) => {
		// lex...
	});
	ast.forEach((node) => {
		// parse...
	})
}

function tokenize(code) {
	let REGEXES = [
		// ...
	];
	let statements = code.split(' ');
	let tokens;
	REGEXES.forEach((REGEX) => {
		statements.forEach((statement) => {
			// ...
		})
	});
	return tokens;
}
function lexer(tokens) {
	let ast;
	tokens.forEach((token) => {
		// lex...
	});
	return ast;
}
function parseBetterJSAlternative(code) {
	let tokens = tokenize(code);
	let ast = lexer(tokens);
	ast.forEach((node) => {
		// parse...
	})
}

function showDeveloperList(developers) {
	developers.forEach(developers => {
		var expectedSalary = developer.calculateExpectedSalary();
		var experience = developer.getExperience();
		var githubLink = developer.getGithubLink();
		var data = {
			expectedSalary: expectedSalary,
			experience: experience,
			githubLink: githubLink
		};
		render(data);
	});
}
function showManagerList(managers) {
	managers.forEach(manager => {
		var expectedSalary = manager.calculateExpectedSalary();
		var experience = manager.getExperience();
		var portfolio = manager.getMBAProjects();
		var data = {
			expectedSalary: expectedSalary,
			experience: experience,
			portfolio: portfolio
		};
		render(data);
	});
}

function showList(employees) {
	employees.forEach(employee => {
		var expectedSalary = employee.calculateExpectedSalary();
		var experience = employee.getExperience();
		var portfolio;
		if (employee.type === 'manager') {
			portfolio = employee.getMBAProjects();
		} else {
			portfolio = employee.getGithubLink();
		}
		var data = {
			expectedSalary: expectedSalary,
			experience: experience,
			portfolio: portfolio
		};
		render(data);
	});
}

function writeForumComment(subject, body) {
	subject = subject || 'No Subject';
	body = body || 'No text';
}

function writeForumComment(subject = 'No subject', body = 'No text') {
	...
}

var menuConfig = {
	title: null,
	body: 'Bar',
	buttonText: null,
	cancellable: true
}
function createMenu(config) {
	config.title = config.title || 'Foo'
	config.body = config.body || 'Bar'
	config.buttonText = config.buttonText || 'Baz'
	config.cancellable = config.cancellable === undefined ? config.cancellable : true;
}
createMenu(menuConfig);

var menuConfig = {
	title: 'Order',
	// User did not include 'body' key
	buttonText: 'Send',
	cancellable: true
}
function createMenu(config) {
	config = Object.assign({
		title: 'Foo',
		body: 'Bar',
		buttonText: 'Baz',
		cancellable: true
	}, config);
	// 现在 config 等于: {title: "Foo", body: "Bar", buttonText: "Baz", cancellable: true}
	// ...
}
createMenu(menuConfig);

function createFile(name, temp) {
	if (temp) {
		fs.create('./temp/' + name);
	} else {
		fs.create(name);
	}
}

function createTempFile(name) {
	fs.create('./temp/' + name);
}
function createFile(name) {
	fs.create(name);
}

// 下面的函数使用了全局变量。
// 如果有另一个函数在使用 name，现在可能会因为 name 变成了数组而不能正常运行。
var name = 'Ryan McDermott';
function splitIntoFirstAndLastName() {
	name = name.split(' ');
}
splitIntoFirstAndLastName();
console.log(name); 
// ['Ryan', 'McDermott'];

function splitIntoFirstAndLastName(name) {
	return name.split(' ');
}
var name = 'Ryan McDermott';
var newName = splitIntoFirstAndLastName(name);
console.log(name); 
// 'Ryan McDermott';console.log(newName); 
// ['Ryan', 'McDermott'];

Array.prototype.diff = function(comparisonArray) {
	var values = [];
	var hash = {};
	for (var i of comparisonArray) {
		hash[i] = true;
	}
	for (var i of this) {
		if (!hash[i]) {
			values.push(i);
		}
	}
	return values;
}

class SuperArray extends Array {
	constructor(...args) {
		super(...args);
	}
	diff(comparisonArray) {
		var values = [];
		var hash = {};
		for (var i of comparisonArray) {
			hash[i] = true;
		}
		for (var i of this) {
			if (!hash[i]) {
				values.push(i);
			}
		}
		return values;
	}
}

const programmerOutput = [
{
	name: 'Uncle Bobby',
	linesOfCode: 500
}, {
	name: 'Suzie Q',
	linesOfCode: 1500
}, {
	name: 'Jimmy Gosling',
	linesOfCode: 150
}, {
	name: 'Gracie Hopper',
	linesOfCode: 1000
}];
var totalOutput = 0;
for (var i = 0; i < programmerOutput.length; i++) {
	totalOutput += programmerOutput[i].linesOfCode;
}

const programmerOutput = [
{
	name: 'Uncle Bobby',
	linesOfCode: 500
}, {
	name: 'Suzie Q',
	linesOfCode: 1500
}, {
	name: 'Jimmy Gosling',
	linesOfCode: 150
}, {
	name: 'Gracie Hopper',
	linesOfCode: 1000
}];
var totalOutput = programmerOutput.map((programmer) => programmer.linesOfCode).reduce((acc, linesOfCode) => acc + linesOfCode, 0);

if (fsm.state === 'fetching' && isEmpty(listNode)) {
	/// ...
}

function shouldShowSpinner(fsm, listNode) {
	return fsm.state === 'fetching' && isEmpty(listNode);
}
if (shouldShowSpinner(fsmInstance, listNodeInstance)) {
	// ...
}

function isDOMNodeNotPresent(node) {
	// ...
}
if (!isDOMNodeNotPresent(node)) {
	// ...
}

function isDOMNodePresent(node) {
	// ...
}
if (isDOMNodePresent(node)) {
	// ...
}

class Airplane {
	//...
	getCruisingAltitude() {
		switch (this.type) {
		case '777':
			return getMaxAltitude() - getPassengerCount();
		case 'Air Force One':
			return getMaxAltitude();
		case 'Cessna':
			return getMaxAltitude() - getFuelExpenditure();
		}
	}
}

class Airplane {
	//...
}
class Boeing777 extends Airplane {
	//...
	getCruisingAltitude() {
		return getMaxAltitude() - getPassengerCount();
	}
}
class AirForceOne extends Airplane {
	//...
	getCruisingAltitude() {
		return getMaxAltitude();
	}
}
class Cessna extends Airplane {
	//...
	getCruisingAltitude() {
		return getMaxAltitude() - getFuelExpenditure();
	}
}

function travelToTexas(vehicle) {
	if (vehicle instanceof Bicycle) {
		vehicle.peddle(this.currentLocation, new Location('texas'));
	} else if (vehicle instanceof Car) {
		vehicle.drive(this.currentLocation, new Location('texas'));
	}
}

function travelToTexas(vehicle) {
	vehicle.move(this.currentLocation, new Location('texas'));
}

function combine(val1, val2) {
	if (typeof val1 == "number" && typeof val2 == "number" ||
	typeof val1 == "string" && typeof val2 == "string") {
		return val1 + val2;
	} else {
		throw new Error('Must be of type String or Number');
	}
}

function combine(val1, val2) {
	return val1 + val2;
}

// 在旧浏览器中，每次循环的成本都比较高，因为每次都会重算 `len`。
// 现在浏览器中，这已经被优化了。
for (var i = 0, len = list.length; i < len; i++) {
	// ...
}

for (var i = 0; i < list.length; i++) {
	// ...
}

function oldRequestModule(url) {
	// ...
}
function newRequestModule(url) {
	// ...
}
var req = newRequestModule;
inventoryTracker('apples', req, 'www.inventory-awesome.io');

function newRequestModule(url) {
	// ...
}
var req = newRequestModule;
inventoryTracker('apples', req, 'www.inventory-awesome.io');

原文：https://github.com/ryanmcdermott/clean-code-javascript/blob/master/README.md
译文：http://www.zcfy.cc/article/clean-code-javascript-readme-md-at-master-ryanmcdermott-clean-code-javascript-github-2273.html
译者：边城