Introduction to methods of using less (variables, mixing, matching, operations, nesting)

高洛峰
Release: 2017-03-17 10:30:34
Original
1783 people have browsed it

How to use less and some commonly used ones (Variables, mixing, matching, operations, nesting)

Less introduction and compilation tools

What is less

1.LESSCSS is a dynamic style language and a type of CSS preprocessing language. It uses a syntax similar to CSS and gives CSS the characteristics of a dynamic language, such as variables and inheritance, operations, functions, etc., make it easier to write and maintain CSS.
LESSCSS can be used in multiple languages ​​and environments, including browsers, desktop clients, and servers.

less's compilation tool

  1. Koala Koala--if there is no CSS folder created during compilation, Koala will automatically generate one for you
    How to set the language
    使用less(变量,混合,匹配,运算,嵌套)的方法介绍
    How to compile
    - 使用less(变量,混合,匹配,运算,嵌套)的方法介绍

  2. Let webstorm support less compilation:

  • Installationnode.js --- This is a package management tool that will be used in the future

  • WIN+ R

  • Enter npm install less

  • ....

  • less Grammar

    Ps: The following knowledge points will use the above knowledge points (for example, variables will be used in mixing to deepen the impression^_^)

    1. Comments

    • // Only displayed in less

    • /**/ Will be compiled during compilation A good css file shows the writing method of

  • variable

    • ##less

      @ly_width:100px;
      .box {
      width:@ly_width;
      }
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    • What is displayed in css after compilation is

      .box {
      width:100px;
      }
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    • define variables with @

  • Mix

    • Solve the border-radius compatibility

      .border_radius (@radius: 5px) {
      -webkit-border-radius: @radius;
      -moz-border-radius: @radius;
      -ms-border-radius: @radius;
      -o-border-radius: @radius;
      border-radius: @radius;
      }
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    • less writing method

      @ly_width:100px;
      @ly_height:200px;
      @ly_color:green;
      .border(@border_width:3px;) {
      border:@border_width solid red;
      }
      .one {
      width:@ly_width;
      height:@ly_height;
      background-color:@ly_color;
      .border();
      }
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    • After compilation, what is displayed in css is the writing method in

      .one {
      width: 100px;
      height: 200px;
      background-color: #008000;
      border: 3px solid #ff0000;
      }
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      ##less
    • @ly_width:100px;
      @ly_height:200px;
      @ly_color:green;
      .border(@border_width) {
      border:@border_width solid red;
      }
      .one {
      width:@ly_width;
      height:@ly_height;
      background-color:@ly_color;
      .border(1px);
      }
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    • What is displayed in the css after compilation is
    • .one {
      width: 100px;
      height: 200px;
      background-color: #008000;
      border: 1px solid #ff0000;
      }
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      First, upload the code in less. What if you want to apply the .border style in .one?
    • @ly_width:100px;
      @ly_height:200px;
      @ly_color:green;
      .border {
      border:1px solid red;
      }
      .one {
      width:@ly_width;
      height:@ly_height;
      background-color:@ly_color;
      }
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    • Write as follows
    • @ly_width:100px;
      @ly_height:200px;
      @ly_color:green;
      .border {
      border:1px solid red;
      }
      .one {
      width:@ly_width;
      height:@ly_height;
      background-color:@ly_color;
      .border;
      }
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    • After compilation, what is displayed in css is
    • .border { border:1px solid red ; } .one { width: 100px; height: 200px; background-color: #008000; border: 1px solid red; }

      without Mixing of parameters
    • Mixing with parameters---without default value (You can pass multiple parameters, separated by commas or semicolons. It is recommended to use semicolons. The following parameters are Example)
    • Mixing with parameters---with default value (multiple parameters can be passed, below is one parameter as an example)
    • In When solving css3 compatibility, we often use the
    matching pattern
    • less writing method
    • //定义上,下,左,右边框的样式
      .border(top;@border_width:5px;@border_color:red){
      border-top:@border_width solid @border_color;
      }
      .border(bottom;@border_width:5px;@border_color:red){
      border-bottom:@border_width solid @border_color;
      }
      .border(left;@border_width:5px;@border_color:red){
      border-left:@border_width solid @border_color;
      }
      .border(right;@border_width:5px;@border_color:red){
      border-right:@border_width solid @border_color;
      }
      //如果想写通用的样式 可以在下面的代码中写 格式是固定的 
      .border(@_,@border_width:5px;@border_color:red){
      border-color:yellow;
      }
      .border_use1 {
      //选择和if差不多 如果是left就调用上面对应的
      .border(left);
      }
      .border_use2 {
      //选择和if差不多 如果是right就调用上面对应的
      .border(right);
      }
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    • What is displayed in the css after compilation is
    • .border_use1 {
      border-left:5px solid #ff0000;
      border-color:yellow;
      }
      .border_use2 {
      border-right:5px solid #ff0000;
      border-color:yellow;
      }
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      can be understood as if is somewhat similar to the above mix
    Operation
    • How to write in less
    • @ly_width:100px;
      .one {
      width:@ly_widht + 100;
      }
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    • What is displayed in css after compilation
    • .one {
      width:200px;
      }
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      Operations provide addition, subtraction, multiplication, and division operations, and can also perform operations on attribute values ​​and colors...
    Nesting
  • ##html structure
      <p class="one">
      <p class="two"></p>
      </p>
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    • Writing in less
    • @ly_width:100px;
      @ly_height:200px;
      @ly_color:red;
      .one {
      width:@ly_width;
      height:@ly_height;
      background-color:@ly_color;
      .two {
          background-color: green;
      }
      }
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    • What is displayed in css after compilation is
    • .one {
      width: 100px;
      height: 200px;
      background-color: #ff0000;
      }
      .one .two {
        background-color: green;
      }
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    • You can nest another selector in a selector, the code looks like Clear hierarchy to improve code maintainability
      • ##@arguments variable
    • How to write in less
    • //和前面提到的混合一起举个栗子  
      .border(@border_width;@border_style;@border_color){
      border:@arguments;
      }
      .one {
      .border(1px;solid;red);
      }
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      • What is displayed in the css after compilation is

        .one {
        border:1px solid #ff0000;
        }
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      • ##can include all variables and process the variables together

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