Javascript coding conventions (coding specifications)
这篇文章主要介绍了Javascript 编码约定(编码规范),需要的朋友可以参考下
1、使用 strict 模式
在一个作用域(包括函数作用域、全局作用域)中,可以使用
"use strict";
来开启 strict 模式。
2、缩进
用 Tab 键进行代码缩进,以节约代码大小,使用4个空格的宽度来进行缩进(JSLint 建议)。
3、符号
1) 大括号
与语句放同一行,放于最后面;仅有一行语句,也使用大括号:
if (true) { //true } else { //false }
while (true) { //alert(1); }
2) 空格
在逗号、分号、冒号后加空格
在操作符前后加空格
在大括号开始符之前
在大括号结束符和 else、while 或 catch 之间
在 for 的各个部分
如:
var a = [1, 2, 3]; var obj = { name: 'name', value: 'value' }; for (var i = 0; i < 10; i++) {} function func(a, b, c) {} c = a + b; if (a && b || c) { //if } else { //else } try { //try } catch(err) { //catch }
3) 所有语句结束后,使用 ; 号结束
4、命名
对象:使用驼峰式,如:MyClass
方法、变量:使用混合式,如:getName(), myName
常量:大写加下划线,如:MY_NAME
5、单一 var 模式
只使用一个 var 在函数顶部进行变量声明,作用如下:
1) 提供一个单一的地址已查找到函数需要的所有局部变量
2) 防止出现变量在定义前就被使用的逻辑错误
3) 帮助牢记要声明变量,尽可能少地使用全局变量
4) 更少的编码
function func() { var a = 1, b = 2, sum = a + b, obj = { name: 'name', value: 'value' }, $btn = $('#btn'); //函数体 }
6、循环
1) for 循环
var i, arr = []; for (i = arr.length; i--;) { //arr[i]; }
注:
for (var i = 0; i < document.getElementsByName().length; i++) { //document.getElementsByName()[0]; }
这种方式每次对 i 进行长度比较的使用对会进行 document 的查询,而通常 DOM 操作是非常耗时的。
2) while 循环
var arr = [], i = arr.length; while (i--) { //处理 }
3) for-in 循环
var i, hasOwn = Object.prototype.hasOwnProperty; for (i in man) { if (hasOwn.call(man, i)) { //过滤 console.log(i, ':', man[i]); } }
7、switch 选择
switch (num) { case 0: //do something break; case 1: //do something break; ... default: //do default }
建议使用:
var obj = { '0': function() { //do somethins }, '1': function() { // do somethis }, ... } if (obj.hasOwnProperty(num)) { obj[num](); } else { //do default }
8、使用 parseInt() 的数值约定
1) 每次都具体指定进制参数:
var month = '09', day = '08'; month = parseInt(month, 10); //不加进制参数便会转换为八进制 day = parseInt(day, 10);
2) 其他常用的将字符串转换为数值的方法:
+'08'; Number('08');
9、字面量模式
不建议使用构造函数来定义:
// built in constructors (avoid) var o = new Object(); var a = new Array(); var re = new RegExp('[a-z]', 'g'); var s = new String(); var n = new Number(); var b = new Boolean(); throw new Error('message');
建议使用更优的字面量模式:
// literals and primitives (prefer) var o = {}; var a = []; var re = /[a-z]/g; var s = ''; var n = 0; var b = false; throw { name: 'Error', message: 'message' }
10、其他
1) 变量内的简写单词如果在开头则全小写:xmlDocument,如果不在开头则全大写:loadXML
2) 变量必须是有意义的英文,禁止拼音
上面是我整理给大家的,希望今后会对大家有帮助。
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