# CSS 代码风格

# 缩进

使用soft tab(2个空格)。

.element {
  position: absolute;
  top: 10px;
  left: 10px;
  border-radius: 10px;
  width: 50px;
  height: 50px;
}

# 分号

每个属性声明末尾都要加分号。

.element {
  width: 20px;
  height: 20px;
  background-color: red;
}

# 空格

以下几种情况不需要空格:

  • 属性名后
  • 多个规则的分隔符,
  • !important !
  • 属性值中(后和)
  • 行末不要有多余的空格

以下几种情况需要空格:

  • 属性值前
  • 选择器>, +, ~前后
  • {
  • !important !
  • @else 前后
  • 属性值中的,
  • 注释/*后和*/
/* not good */
.element {
  color :red! important;
  background-color: rgba(0,0,0,.5);
}

/* good */
.element {
  color: red !important;
  background-color: rgba(0, 0, 0, .5);
}

/* not good */
.element ,
.dialog{
  ...
}

/* good */
.element,
.dialog {

}

/* not good */
.element>.dialog{
  ...
}

/* good */
.element > .dialog{
  ...
}

/* not good */
.element{
  ...
}

/* good */
.element {
  ...
}

/* not good */
@if{
  ...
}@else{
  ...
}

/* good */
@if {
  ...
} @else {
  ...
}

# 空行

以下几种情况需要空行:

  • 文件最后保留一个空行
  • }后最好跟一个空行,包括scss中嵌套的规则
  • 属性之间需要适当的空行,具体见属性声明顺序
/* not good */
.element {
  ...
}
.dialog {
  color: red;
  &:after {
      ...
  }
}

/* good */
.element {
  ...
}

.dialog {
  color: red;

  &:after {
      ...
  }
}

# 换行

以下几种情况不需要换行:

  • {

以下几种情况需要换行:

  • {后和}
  • 每个属性独占一行
  • 多个规则的分隔符,
/* not good */
.element {
  color: red;
  background-color: black;
}

/* good */
.element {
  color: red;
  background-color: black;
}

/* not good */
.element, .dialog {
  ...
}

/* good */
.element,
.dialog {
  ...
}

# 注释

注释统一用/* */(scss中也不要用//),具体参照右边的写法;

缩进与下一行代码保持一致;

可位于一个代码行的末尾,与代码间隔一个空格。

/* Modal header */
.modal-header {
  ...
}

/*
* Modal header
*/
.modal-header {
  ...
}

.modal-header {
  /* 50px */
  width: 50px;
  color: red; /* color red */
}

# 引号

最外层统一使用双引号;

url的内容要用引号;

属性选择器中的属性值需要引号。

.element:after {
  content: "";
  background-image: url("logo.png");
}

li[data-type="single"] {
  ...
}

# 命名

  • 类名使用小写字母,以中划线分隔
  • id采用驼峰式命名
  • scss中的变量、函数、混合、placeholder采用驼峰式命名
/* class */
.element-content {
    ...
}

/* id */
#myDialog {
  ...
}

/* 变量 */
$colorBlack: #000;

/* 函数 */
@function pxToRem($px) {
  ...
}

/* 混合 */
@mixin centerBlock {
  ...
}

/* placeholder */
%myDialog {
  ...
}

# 属性声明顺序

相关的属性声明按右边的顺序做分组处理,组之间需要有一个空行。

.declaration-order {
  display: block;
  float: right;

  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  z-index: 100;

  border: 1px solid #e5e5e5;
  border-radius: 3px;
  width: 100px;
  height: 100px;

  font: normal 13px "Helvetica Neue", sans-serif;
  line-height: 1.5;
  text-align: center;

  color: #333;
  background-color: #f5f5f5;

  opacity: 1;
}
// 下面是推荐的属性的顺序
[
  [
      "display",
      "visibility",
      "float",
      "clear",
      "overflow",
      "overflow-x",
      "overflow-y",
      "clip",
      "zoom"
  ],
  [
      "table-layout",
      "empty-cells",
      "caption-side",
      "border-spacing",
      "border-collapse",
      "list-style",
      "list-style-position",
      "list-style-type",
      "list-style-image"
  ],
  [
      "-webkit-box-orient",
      "-webkit-box-direction",
      "-webkit-box-decoration-break",
      "-webkit-box-pack",
      "-webkit-box-align",
      "-webkit-box-flex"
  ],
  [
      "position",
      "top",
      "right",
      "bottom",
      "left",
      "z-index"
  ],
  [
      "margin",
      "margin-top",
      "margin-right",
      "margin-bottom",
      "margin-left",
      "-webkit-box-sizing",
      "-moz-box-sizing",
      "box-sizing",
      "border",
      "border-width",
      "border-style",
      "border-color",
      "border-top",
      "border-top-width",
      "border-top-style",
      "border-top-color",
      "border-right",
      "border-right-width",
      "border-right-style",
      "border-right-color",
      "border-bottom",
      "border-bottom-width",
      "border-bottom-style",
      "border-bottom-color",
      "border-left",
      "border-left-width",
      "border-left-style",
      "border-left-color",
      "-webkit-border-radius",
      "-moz-border-radius",
      "border-radius",
      "-webkit-border-top-left-radius",
      "-moz-border-radius-topleft",
      "border-top-left-radius",
      "-webkit-border-top-right-radius",
      "-moz-border-radius-topright",
      "border-top-right-radius",
      "-webkit-border-bottom-right-radius",
      "-moz-border-radius-bottomright",
      "border-bottom-right-radius",
      "-webkit-border-bottom-left-radius",
      "-moz-border-radius-bottomleft",
      "border-bottom-left-radius",
      "-webkit-border-image",
      "-moz-border-image",
      "-o-border-image",
      "border-image",
      "-webkit-border-image-source",
      "-moz-border-image-source",
      "-o-border-image-source",
      "border-image-source",
      "-webkit-border-image-slice",
      "-moz-border-image-slice",
      "-o-border-image-slice",
      "border-image-slice",
      "-webkit-border-image-width",
      "-moz-border-image-width",
      "-o-border-image-width",
      "border-image-width",
      "-webkit-border-image-outset",
      "-moz-border-image-outset",
      "-o-border-image-outset",
      "border-image-outset",
      "-webkit-border-image-repeat",
      "-moz-border-image-repeat",
      "-o-border-image-repeat",
      "border-image-repeat",
      "padding",
      "padding-top",
      "padding-right",
      "padding-bottom",
      "padding-left",
      "width",
      "min-width",
      "max-width",
      "height",
      "min-height",
      "max-height"
  ],
  [
      "font",
      "font-family",
      "font-size",
      "font-weight",
      "font-style",
      "font-variant",
      "font-size-adjust",
      "font-stretch",
      "font-effect",
      "font-emphasize",
      "font-emphasize-position",
      "font-emphasize-style",
      "font-smooth",
      "line-height",
      "text-align",
      "-webkit-text-align-last",
      "-moz-text-align-last",
      "-ms-text-align-last",
      "text-align-last",
      "vertical-align",
      "white-space",
      "text-decoration",
      "text-emphasis",
      "text-emphasis-color",
      "text-emphasis-style",
      "text-emphasis-position",
      "text-indent",
      "-ms-text-justify",
      "text-justify",
      "letter-spacing",
      "word-spacing",
      "-ms-writing-mode",
      "text-outline",
      "text-transform",
      "text-wrap",
      "-ms-text-overflow",
      "text-overflow",
      "text-overflow-ellipsis",
      "text-overflow-mode",
      "-ms-word-wrap",
      "word-wrap",
      "-ms-word-break",
      "word-break"
  ],
  [
      "color",
      "background",
      "filter:progid:DXImageTransform.Microsoft.AlphaImageLoader",
      "background-color",
      "background-image",
      "background-repeat",
      "background-attachment",
      "background-position",
      "-ms-background-position-x",
      "background-position-x",
      "-ms-background-position-y",
      "background-position-y",
      "-webkit-background-clip",
      "-moz-background-clip",
      "background-clip",
      "background-origin",
      "-webkit-background-size",
      "-moz-background-size",
      "-o-background-size",
      "background-size"
  ],
  [
      "outline",
      "outline-width",
      "outline-style",
      "outline-color",
      "outline-offset",
      "opacity",
      "filter:progid:DXImageTransform.Microsoft.Alpha(Opacity",
      "-ms-filter:\\'progid:DXImageTransform.Microsoft.Alpha",
      "-ms-interpolation-mode",
      "-webkit-box-shadow",
      "-moz-box-shadow",
      "box-shadow",
      "filter:progid:DXImageTransform.Microsoft.gradient",
      "-ms-filter:\\'progid:DXImageTransform.Microsoft.gradient",
      "text-shadow"
  ],
  [
      "-webkit-transition",
      "-moz-transition",
      "-ms-transition",
      "-o-transition",
      "transition",
      "-webkit-transition-delay",
      "-moz-transition-delay",
      "-ms-transition-delay",
      "-o-transition-delay",
      "transition-delay",
      "-webkit-transition-timing-function",
      "-moz-transition-timing-function",
      "-ms-transition-timing-function",
      "-o-transition-timing-function",
      "transition-timing-function",
      "-webkit-transition-duration",
      "-moz-transition-duration",
      "-ms-transition-duration",
      "-o-transition-duration",
      "transition-duration",
      "-webkit-transition-property",
      "-moz-transition-property",
      "-ms-transition-property",
      "-o-transition-property",
      "transition-property",
      "-webkit-transform",
      "-moz-transform",
      "-ms-transform",
      "-o-transform",
      "transform",
      "-webkit-transform-origin",
      "-moz-transform-origin",
      "-ms-transform-origin",
      "-o-transform-origin",
      "transform-origin",
      "-webkit-animation",
      "-moz-animation",
      "-ms-animation",
      "-o-animation",
      "animation",
      "-webkit-animation-name",
      "-moz-animation-name",
      "-ms-animation-name",
      "-o-animation-name",
      "animation-name",
      "-webkit-animation-duration",
      "-moz-animation-duration",
      "-ms-animation-duration",
      "-o-animation-duration",
      "animation-duration",
      "-webkit-animation-play-state",
      "-moz-animation-play-state",
      "-ms-animation-play-state",
      "-o-animation-play-state",
      "animation-play-state",
      "-webkit-animation-timing-function",
      "-moz-animation-timing-function",
      "-ms-animation-timing-function",
      "-o-animation-timing-function",
      "animation-timing-function",
      "-webkit-animation-delay",
      "-moz-animation-delay",
      "-ms-animation-delay",
      "-o-animation-delay",
      "animation-delay",
      "-webkit-animation-iteration-count",
      "-moz-animation-iteration-count",
      "-ms-animation-iteration-count",
      "-o-animation-iteration-count",
      "animation-iteration-count",
      "-webkit-animation-direction",
      "-moz-animation-direction",
      "-ms-animation-direction",
      "-o-animation-direction",
      "animation-direction"
  ],
  [
      "content",
      "quotes",
      "counter-reset",
      "counter-increment",
      "resize",
      "cursor",
      "-webkit-user-select",
      "-moz-user-select",
      "-ms-user-select",
      "user-select",
      "nav-index",
      "nav-up",
      "nav-right",
      "nav-down",
      "nav-left",
      "-moz-tab-size",
      "-o-tab-size",
      "tab-size",
      "-webkit-hyphens",
      "-moz-hyphens",
      "hyphens",
      "pointer-events"
  ]
]

# 颜色

颜色16进制用小写字母;

颜色16进制尽量用简写。

/* not good */
.element {
  color: #ABCDEF;
  background-color: #001122;
}

/* good */
.element {
  color: #abcdef;
  background-color: #012;
}

# 属性简写

属性简写需要你非常清楚属性值的正确顺序,而且在大多数情况下并不需要设置属性简写中包含的所有值,所以建议尽量分开声明会更加清晰;

margin 和 padding 相反,需要使用简写;

常见的属性简写包括:

  • font
  • background
  • transition
  • animation
/* not good */
.element {
  transition: opacity 1s linear 2s;
}

/* good */
.element {
  transition-delay: 2s;
  transition-timing-function: linear;
  transition-duration: 1s;
  transition-property: opacity;
}

# 媒体查询

尽量将媒体查询的规则靠近与他们相关的规则,不要将他们一起放到一个独立的样式文件中,或者丢在文档的最底部,这样做只会让大家以后更容易忘记他们。

.element {
  ...
}

.element-avatar{
  ...
}

@media (min-width: 480px) {
  .element {
      ...
  }

  .element-avatar {
      ...
  }
}

# SCSS相关

提交的代码中不要有 @debug

声明顺序:

  • @extend
  • 不包含 @content@include
  • 包含 @content@include
  • 自身属性
  • 嵌套规则

@import 引入的文件不需要开头的'_'和结尾的'.scss';

嵌套最多不能超过5层;

@extend 中使用placeholder选择器;

去掉不必要的父级引用符号'&'。

/* not good */
@import "_dialog.scss";

/* good */
@import "dialog";

/* not good */
.fatal {
  @extend .error;
}

/* good */
.fatal {
  @extend %error;
}

/* not good */
.element {
  & > .dialog {
      ...
  }
}

/* good */
.element {
  > .dialog {
      ...
  }
}

# 杂项

不允许有空的规则;

元素选择器用小写字母;

去掉小数点前面的0

去掉数字中不必要的小数点和末尾的0;

属性值0后面不要加单位;

同个属性不同前缀的写法需要在垂直方向保持对齐,具体参照右边的写法;

无前缀的标准属性应该写在有前缀的属性后面;

不要在同个规则里出现重复的属性,如果重复的属性是连续的则没关系;

不要在一个文件里出现两个相同的规则;

border: 0; 代替 border: none;

选择器不要超过4层(在scss中如果超过4层应该考虑用嵌套的方式来写);

发布的代码中不要有 @import

尽量少用*选择器。

/* not good */
.element {
}

/* not good */
LI {
  ...
}

/* good */
li {
  ...
}

/* not good */
.element {
  color: rgba(0, 0, 0, 0.5);
}

/* good */
.element {
  color: rgba(0, 0, 0, .5);
}

/* not good */
.element {
  width: 50.0px;
}

/* good */
.element {
  width: 50px;
}

/* not good */
.element {
  width: 0px;
}

/* good */
.element {
  width: 0;
}

/* not good */
.element {
  border-radius: 3px;
  -webkit-border-radius: 3px;
  -moz-border-radius: 3px;

  background: linear-gradient(to bottom, #fff 0, #eee 100%);
  background: -webkit-linear-gradient(top, #fff 0, #eee 100%);
  background: -moz-linear-gradient(top, #fff 0, #eee 100%);
}

/* good */
.element {
  -webkit-border-radius: 3px;
     -moz-border-radius: 3px;
          border-radius: 3px;

  background: -webkit-linear-gradient(top, #fff 0, #eee 100%);
  background:    -moz-linear-gradient(top, #fff 0, #eee 100%);
  background:         linear-gradient(to bottom, #fff 0, #eee 100%);
}

/* not good */
.element {
  color: rgb(0, 0, 0);
  width: 50px;
  color: rgba(0, 0, 0, .5);
}

/* good */
.element {
  color: rgb(0, 0, 0);
  color: rgba(0, 0, 0, .5);
}