如何正确使用javascript 来进行我们的程序开发_javascript技巧

今天在github 上面找到了一个关于如何正确使用javascript 来进行我们的程序开发.我就恬不知耻的来了个原创啊..坑爹啊.拿来和大家分享一下吧.
A mostly reasonable approach to Javascript.
Types //类型
Objects //对象
Arrays //数组
Strings //字符串
Functions //函数
Properties //属性
Variables //变量
Hoisting //变量提升
Conditional Expressions & Equality //条件表达式和等式.
Blocks //块代码
Comments //注释
Whitespace //空格
Commas //逗号
Semicolons //分号
Type Casting & Coercion //类型转换
Naming Conventions //命名规则
Accessors //访问
Constructors //构造器
Events //时间
Modules //模型
jQuery //
ECMAScript 5 Compatibility //ECMA 5 兼容
Testing //测试
Performance //性能
Resources //资源
In the Wild
Translation
The JavaScript Style Guide Guide
Contributors
License

Types (类型)
原始类型: 当访问一个原始类型的时候,其实直接访问该原始类型的内容.
string
number
boolean
null
undefined
var foo = 1,
bar = foo;
bar = 9;
console.log(foo,bar); //=> 1,9

复杂类型: 当你访问一个复杂类型数据类型的时候,其实是通过引用访问该变量的值.
object
array
function

var foo = [1,2];
bar = foo;
bar[0] = 9;
console.log(foo[0],bar[0]); // => 9,9

object(对象)
使用对象字面量来创建对象 (literal)

//bad
var item = new Object();
//good
var item = {};

不要使用保留关键字作为对象的属性名.这在IE8下无法工作.

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

array(数组)
同样使用 字面量方法来创建数组

//bad
var items = new Array();
//good
var items = [];

如果你不知道数组的长度,那么使用Array的内置方法push进行插入操作

var someStack = [];
//bad
someStack[someStack.length] = 'vein';
//good
someStack.push('vein');

当你想要拷贝一个数组的时候,使用array.slice

var len = items.length, //指的就是上面的内容...
itemCopy = [],
i;
//bad
for(i = 0; i < len ; ++i){
itemCopy[i] = items[i];
}
//good
itemCopy = items.slice(); //这里要注意了.这个我还真不知道...

Strings 字符串
使用单引号 (single quotes ) 来包围字符串...//这里我没有找到合适的关于性能方面的解释,我个人也喜欢这么用,(穿的少总比穿得多好看点吧..你懂得..)

//bad
var name = "Bob Parr";
//good
var name = 'Bob Parr';
//bad
var fullName = "Bob " + this.lastName;
//good
var fullName = 'Bob ' + this.lastName;

字符串长于80个字符的时候需要使用字符串连接在多行进行编写..注意,如果过度使用,连接字符串将会影响性能(performance)

// bad
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.';
// bad
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.';
// good
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.';

如果是有计划的 建立一个数组,像下面这样.使用Array.join 效果会更好..

var items,
messages,
length,
i;
messages = [{
stat: 'success',
message: ' This one worked'
},{
stat: 'success',
message: ' This one worked'
},{
stat: 'success',
message: ' This one worked'
}
];
length = messages.length;
//bad
function inbox(messages){
items = '<ul>';
for (i = 0; i < length; i++) {
items += '<li>' + messages[i].message + '</li>';
}
return items + '</ul>';
}
//good
function inbox(messages){
items = [];
for( i = 0; i < length ; i++){
items[i] = messages[i].message;
}
return '<ul><li>' + items.join('</li><li>') + '</li></ul>';
}

函数(Functions)

//匿名函数表达式..
var anonymous = function(){
return true;
};
// 命名函数表达式.
var named = function named(){
return true;
};
//即时引用函数
(function(){
console.log('Welcome to the Internet. Please follow me.');
})();

永远不要在非函数的块代码(if,while)中定义函数.相应的,在代码块中间函数赋值给外部的变量名..

//bad
if(currentUser){
function test(){
console.log('Nope.');
}
}
//good
var test;
if(currentUser){
test = function(){
console.log('Yup'); 
}; //be careful with the semi-colon.
}

Properties (属性)
使用点语法来访问属性.

var luke = {
jedi: true,
age: 28
};
//bad
var isJedi = luke['jedi'];
//good
var isJedi = luck.jedi;

当使用变量访问对象属性时,使用 [] 方括号来访问

var luke = {
jedi: true,
age: 28
};
function getProp(prop) {
return luke[prop];
}
var isJedi = getProp('jedi');