整理了一份 Javascript 代码书写规范

var items = getItems(),
    goSportsTeam = true,
    dragonball = 'z';

function() {
  var name = getName();

  test();
  console.log('doing stuff..');

  //..other stuff..

  if (name === 'test') {
    return false;
  }

  return name;
}

var name = 'Bob Parr';

var fullName = 'Bob ' + this.lastName;

var errorMessage = 'This is a super long error that was thrown because ' +
  'of Batman. When you stop to think about how Batman had anything to do ' +
  'with this, you would get nowhere fast.';

var items,
 	messages,
 	length,
 	i;

messages = [{
  state: 'success',
  message: 'This one worked.'
}, {
  state: 'success',
  message: 'This one worked as well.'
}, {
  state: 'error',
  message: 'This one did not work.'
}];

length = messages.length;


function inbox(messages) {
  items = [];

  for (i = 0; i < length; i++) {
    items[i] = '<li>' + messages[i].message + '</li>';
  }

  return '<ul>' + items.join('') + '</ul>';
}

var a = [x1, x2, x3];
var a2 = [x1, x2];
var a3 = [x1];
var a4 = [];

var someStack = [];

someStack.push('abracadabra');

var len = items.length;
var itemsCopy = [];
var i;

itemsCopy = items.slice();

// 匿名 function 表达式
var anonymous = function() {
  return true;
};

// 命名 function 表达式
var named = function named() {
  return true;
};

// 立即执行 function 表达式 
(function() {
  console.log('Welcome to the Internet. Please follow me.');
})();

var test;
if (currentUser) {
  test = function test() {
    console.log('Yup.');
  };
}

// bad
function nope(name, options, arguments) {
  // ...stuff...
}

// good
function yup(name, options, args) {
  // ...stuff...
}

('#items')
  .find('.selected')
    .highlight()
    .end()
  .find('.open')
    .updateCount();

var leds = stage.selectAll('.led')
    .data(data)
  .enter().append('svg:svg')
    .classed('led', true)
    .attr('width', (radius + margin) * 2)
  .append('svg:g')
    .attr('transform', 'translate(' + (radius + margin) + ',' + (radius + margin) + ')')
    .call(tron.led);

var item = {};
var item2 = {
  a: 0,
  b: 1,
  c: 2,
  'strange key': 3
};

// bad
var superman = {
  default: { clark: 'kent' },
  private: true
};

// good
var superman = {
  defaults: { clark: 'kent' },
  hidden: true
};

// bad
var superman = {
  class: 'alien'
};

// good
var superman = {
  type: 'alien'
};

var luke = {
  jedi: true,
  age: 28
};
var isJedi = luke.jedi;//使用 . 访问对象的属性

var luke = {
  jedi: true,
  age: 28
};

function getProp(prop) {
  return luke[prop];
}

var isJedi = getProp('jedi');

if ([0]) {
  // true
  // Objects 等价于 true,数组也是对象
}

// bad
if (name !== '') {
  // ...stuff...
}

// good
if (name) {
  // ...stuff...
}

// bad
if (collection.length > 0) {
  // ...stuff...
}

// good
if (collection.length) {
  // ...stuff...
}

if (test) return false;

if (test) {
  thing1();
  thing2();
} else {
  thing3();
}

var i,
    length = 100;

for ( i = 0; i < length; i++ ) {
  // 语句
}

var prop;
for ( prop in object ) {
  // 语句
}

var obj = {
  foo: function() {
  },

  bar: function() {
  }
};

return obj;

/**
 * make() returns a new element
 * based on the passed in tag name
 *
 * @param {String} tag
 * @return {Element} element
 */
 function make(tag) {

  // ...stuff...

  return element;
}

// good
// is current tab
var active = true;

function getType() {
  console.log('fetching type...');

  // set the default type to 'no type'
  var type = this._type || 'no type';

  return type;
}

// 使用 FIXME 标注一个问题
function Calculator() {

  // FIXME: shouldn't use a global here
  total = 0;

  return this;
}

// 使用 TODO 标注问题的解决方案
function Calculator() {

  // TODO: total should be configurable by an options param
  this.total = 0;

  return this;
}

var x = y + 5;

(function() {
  var name = 'Skywalker';
  return name;
})();

var inputValue = '4';

var val = Number(inputValue);

//or

var val = parseInt(inputValue, 10);

var age = 0;

var hasAge = Boolean(age);

//or

var hasAge = !!age;

var MD5_key = 'ya23adfuodf4sd';

var thisIsMyObject = {};
function thisIsMyFunction() {}

rNumber = /(\d)+/;

function User(options) {
  this.name = options.name;
}

var good = new User({
  name: 'yup'
});

this._firstName = 'Panda';

function() {
  var _this = this;
  return function() {
    console.log(_this);
  };
}

var $sidebar = $('.sidebar');

// bad
function foo(element, a, b) {
  element.onclick = function() { /* uses a and b */ };
}

// good
function foo(element, a, b) {
  element.onclick = bar(a, b);
}

function bar(a, b) {
  return function() { /* uses a and b */ };
}

// bad
Foo.prototype.dispose = function() {
  delete this.property_;
};

// good
Foo.prototype.dispose = function() {
  this.property_ = null;
};

{
  "name": "Alice",
  "id": 31502,
  "email": "looking_glass@example.com"
}

var userInfo = JSON.parse(feed);

var email = userInfo['email'];