17

我将 LESS 引入一个大型 Web 应用程序项目以简化我的 CSS。我有一些 CSS 规则将转换应用于不同数量的属性，例如：

.movable {
    transition-property: top, left;
    transition-duration: 0.2s;
    transition-timing-function: ease;
}

.fadeAndStretchable {
    transition-property: opacity, width, height, margin;
    transition-duration: 1.5s;
    transition-timing-function: ease-out;
}

（注意：为简洁起见，我在这里省略了-webkit,-moz和-o属性：实际上，这些规则中的每一个都是 12 行而不是 3 行。）

请注意， 的值以transition-property逗号分隔。这在 CSS 中是不寻常的：多个值通常用空格分隔（如border: 1px solid #f00）。LESS mixin 可以使用特殊@arguments值来生成所有 mixin 参数的空格分隔列表- 但是是否可以定义一个 LESS mixin，它接受可变数量的参数并将它们转换为逗号分隔的值列表，适用于transition-property？

如有必要，我对需要两个 mixin 的解决方案感到满意：一个 for transition-property，另一个 for transition-durationand transition-timing-function。这是我到目前为止所尝试的：

尝试 1：使用带有未命名参数的 @arguments

.transition-property() {
    -webkit-transition-property: @arguments;
    -moz-transition-property: @arguments;
    -o-transition-property: @arguments;
    transition-property: @arguments;
}

.movable {
    .transition-property(top, left);
}

结果：LESS 错误（“没有为 '.transition-property(top, left)' 找到匹配的定义”）

尝试 2：使用带有命名参数的 @arguments

.transition-property(@p1, @p2, @p3, @p4, @p5) {
    -webkit-transition-property: @arguments;
    -moz-transition-property: @arguments;
    -o-transition-property: @arguments;
    transition-property: @arguments;
}

.movable {
    .transition-property(top, left);
}

结果：LESS 错误（“没有为 '.transition-property(top, left)' 找到匹配的定义”）

尝试 3：使用具有虚拟默认值的命名参数

.transition-property(@p1:p1, @p2:p2, @p3:p3, @p4:p4, @p5:p5) {
    -webkit-transition-property: @p1, @p2, @p3, @p4, @p5;
    -moz-transition-property:  @p1, @p2, @p3, @p4, @p5;
    -o-transition-property:  @p1, @p2, @p3, @p4, @p5;
    transition-property:  @p1, @p2, @p3, @p4, @p5;
}

.movable {
    .transition-property(top, left);
}

结果：没有 LESS 错误，但它会生成一个 CSS 规则-webkit-transition-property: top, left, p3, p4, p5，由于无法识别的属性，浏览器会忽略该规则。

我尝试了各种其他方法（例如将属性作为字符串传递'top,left'），但结果都是一样的：要么是 LESS 错误，要么是无效的 CSS。

有没有办法解决这个问题？还是我必须硬着头皮定义一组在arity上重载的mixin，例如

.transition-property(@p1) {...}
.transition-property(@p1, @p2) {...}
.transition-property(@p1, @p2, @p3) {...}
.transition-property(@p1, @p2, @p3, @p4) {...}
etc.
4

4 回答 4

29

由于Luke Page向我指出了...语法，我已经设法弄清楚了。

解决方案是使用以下内容：

呸。这是生成的混合：

.transition-properties(...) {
    -webkit-transition-property: ~`"@{arguments}".replace(/[\[\]]/g, '')`;
}

这是带有完整浏览器扩展集的完整版本：

.transition-properties(...) {
    @props: ~`"@{arguments}".replace(/[\[\]]/g, '')`;
    -webkit-transition-property: @props;
    -moz-transition-property: @props;
    -o-transition-property: @props;
    transition-property: @props;
}
于 2012-05-02T12:05:59.380 回答
22

也许我误解了你的需求。为什么不能使用转义字符串？

像这样：

.transition ( @property, @duration, @style: ease-in-out ) {
  -webkit-transition-property: @property;  
  -webkit-transition-duration: @duration;
  -webkit-transition-timing-function: @style;

  -moz-transition-property: @property;  
  -moz-transition-duration: @duration;
  -moz-transition-timing-function: @style;

  -ms-transition-property: @property;  
  -ms-transition-duration: @duration;
  -ms-transition-timing-function: @style;

  -o-transition-property: @property;  
  -o-transition-duration: @duration;
  -o-transition-timing-function: @style;

  transition-property: @property;  
  transition-duration: @duration;
  transition-timing-function: @style;
}

#my-id {
  .transition( ~"background, border-color, color", 2s );
}

这正是我们用于多属性转换的方法。从来没有遇到过问题。

于 2012-08-16T08:04:46.793 回答
7

灵活（LESS 1.5.1+）

此解决方案不使用任何内联 javascript，它允许：

  1. 要设置的默认值
  2. 要传递的任意数量的属性、持续时间、延迟等
  3. 以长格式或紧凑格式输出
  4. 如果需要，输入原始列表而不是输入参数组

如果属性的数量大于持续时间、延迟或计时的数量，那么如果compact设置了输出，则持续时间/延迟/计时的最终值将成为超出传递数量的所有其他属性的该参数的值，但是如果compact未设置，则输出长格式，并根据浏览器对 css 标准的解释复制值。

少混音

.transition (@props: all; 
             @duration:1s; 
             @delay: 0s; 
             @timing: ease; 
             @compact: true;
             @raw-input: false) {
  .output() when (@raw-input = false) and not (@compact = true) {
  -webkit-transition-property:@props; 
     -moz-transition-property:@props;
      -ms-transition-property:@props;
       -o-transition-property:@props; 
          transition-property:@props;
  -webkit-transition-duration:@duration; 
     -moz-transition-duration:@duration;
      -ms-transition-duration:@duration;
       -o-transition-duration:@duration; 
          transition-duration:@duration;
  -webkit-transition-delay:   @delay; 
     -moz-transition-delay:   @delay;
      -ms-transition-delay:   @delay;
       -o-transition-delay:   @delay; 
          transition-delay:   @delay;
  -webkit-transition-timing-function:@timing; 
     -moz-transition-timing-function:@timing;
      -ms-transition-timing-function:@timing;
       -o-transition-timing-function:@timing; 
          transition-timing-function:@timing;
  }
  .output() when (@raw-input = false) and (@compact = true) {
    @propsLength: length(@props);
    @durationLength: length(@duration);
    @delayLength: length(@delay);
    @timingLength: length(@timing);
    .buildString(@i, @s: ~'') when (@i <= @propsLength) {
      @prop: extract(@props, @i);
      .setDuration() when (@i <= @durationLength) {
        @dur: extract(@duration, @i);
      }
      .setDuration() when (@i > @durationLength) {
        @dur: extract(@duration, @durationLength);
      }
      .setDuration();
      .setDelay() when (@i <= @delayLength) {
        @del: extract(@delay, @i);
      }
      .setDelay() when (@i > @delayLength) {
        @del: extract(@delay, @delayLength);
      }
      .setDelay();
      .setTiming() when (@i <= @timingLength) {
        @time: extract(@timing, @i);
      }
      .setTiming() when (@i > @timingLength) {
        @time: extract(@timing, @timingLength);
      }
      .setTiming();
      .setDivider() when (@i > 1) {
        @divider: ~'@{s},';
      }
      .setDivider() when (@i = 1) {
        @divider: ~'';
      }
      .setDivider();
      @string: @divider @prop @dur @del @time;
      .buildString((@i + 1), @string);  
    }
    .buildString(1);
    .buildString(@i, @s: ~'') when (@i > @propsLength) {
      .compact(@s);
    }
  }
  .output() when not (@raw-input = false) {
    .compact(@raw-input);
  }
  .compact(@string) {
    -webkit-transition:@string; 
       -moz-transition:@string;
        -ms-transition:@string;
         -o-transition:@string; 
            transition:@string;    
  }
  .output();
}

LESS 使用示例

.test {
  .transition();
}
.test-props {
  .transition(width);
}
.test-duration {
  .transition(@duration: 3s);
}
.test-delay {
  .transition(@delay: 10s);
}
.test-timing {
  .transition(@timing: linear);
}
.test-all {
  .transition(height, 4s, 12s, ease-out);
}
.test-multitransitions {
  .transition(width, height, top; 1s, 2s; 0s, 1s, 3s; ease-in, ease-out, ease);
}
.test-not-compact {
  .transition(width, height, top; 1s, 2s; 0s, 1s, 3s; ease-in, ease-out, ease; false);
}
.test-raw-input {
  .transition(@raw-input: top 1s, bottom 1s, color 3s 1s linear;);
}

在上面的例子中，需要特别注意两点：（1）如何传递多个值，使用逗号分隔列表，使用分号分隔参数组。所以为了形象化，它是这样的：

  .transition(width, height, top; 1s, 2s; 0s, 1s, 3s; ease-in, ease-out, ease);
              |---Properties----|-Dur.--|---Delay---|---------Timing--------|
                                |       |           |
                          semicolons divide groups of parameters

(2) 该raw-input示例如何需要一个结束分号才能将逗号视为列表项：

  .transition(@raw-input: top 1s, bottom 1s, color 3s 1s linear;);
                                                               |
                                                    semicolon here needed

示例的 CSS 输出

.test {
  -webkit-transition:  all 1s 0s ease;
  -moz-transition:  all 1s 0s ease;
  -ms-transition:  all 1s 0s ease;
  -o-transition:  all 1s 0s ease;
  transition:  all 1s 0s ease;
}
.test-props {
  -webkit-transition:  width 1s 0s ease;
  -moz-transition:  width 1s 0s ease;
  -ms-transition:  width 1s 0s ease;
  -o-transition:  width 1s 0s ease;
  transition:  width 1s 0s ease;
}
.test-duration {
  -webkit-transition:  all 3s 0s ease;
  -moz-transition:  all 3s 0s ease;
  -ms-transition:  all 3s 0s ease;
  -o-transition:  all 3s 0s ease;
  transition:  all 3s 0s ease;
}
.test-delay {
  -webkit-transition:  all 1s 10s ease;
  -moz-transition:  all 1s 10s ease;
  -ms-transition:  all 1s 10s ease;
  -o-transition:  all 1s 10s ease;
  transition:  all 1s 10s ease;
}
.test-timing {
  -webkit-transition:  all 1s 0s linear;
  -moz-transition:  all 1s 0s linear;
  -ms-transition:  all 1s 0s linear;
  -o-transition:  all 1s 0s linear;
  transition:  all 1s 0s linear;
}
.test-all {
  -webkit-transition:  height 4s 12s ease-out;
  -moz-transition:  height 4s 12s ease-out;
  -ms-transition:  height 4s 12s ease-out;
  -o-transition:  height 4s 12s ease-out;
  transition:  height 4s 12s ease-out;
}
.test-multitransitions {
  -webkit-transition:  width 1s 0s ease-in, height 2s 1s ease-out, top 2s 3s ease;
  -moz-transition:  width 1s 0s ease-in, height 2s 1s ease-out, top 2s 3s ease;
  -ms-transition:  width 1s 0s ease-in, height 2s 1s ease-out, top 2s 3s ease;
  -o-transition:  width 1s 0s ease-in, height 2s 1s ease-out, top 2s 3s ease;
  transition:  width 1s 0s ease-in, height 2s 1s ease-out, top 2s 3s ease;
}
.test-not-compact {
  -webkit-transition-property: width, height, top;
  -moz-transition-property: width, height, top;
  -ms-transition-property: width, height, top;
  -o-transition-property: width, height, top;
  transition-property: width, height, top;
  -webkit-transition-duration: 1s, 2s;
  -moz-transition-duration: 1s, 2s;
  -ms-transition-duration: 1s, 2s;
  -o-transition-duration: 1s, 2s;
  transition-duration: 1s, 2s;
  -webkit-transition-delay: 0s, 1s, 3s;
  -moz-transition-delay: 0s, 1s, 3s;
  -ms-transition-delay: 0s, 1s, 3s;
  -o-transition-delay: 0s, 1s, 3s;
  transition-delay: 0s, 1s, 3s;
  -webkit-transition-timing-function: ease-in, ease-out, ease;
  -moz-transition-timing-function: ease-in, ease-out, ease;
  -ms-transition-timing-function: ease-in, ease-out, ease;
  -o-transition-timing-function: ease-in, ease-out, ease;
  transition-timing-function: ease-in, ease-out, ease;
}    
.test-raw-input {
  -webkit-transition: top 1s, bottom 1s, color 3s 1s linear;
  -moz-transition: top 1s, bottom 1s, color 3s 1s linear;
  -ms-transition: top 1s, bottom 1s, color 3s 1s linear;
  -o-transition: top 1s, bottom 1s, color 3s 1s linear;
  transition: top 1s, bottom 1s, color 3s 1s linear;
}

如果不需要长格式，那么 mixin 代码可以简化为：

.transition (@props: all; 
             @duration:1s; 
             @delay: 0s; 
             @timing: ease; 
             @raw-input: false) {
  .output() when (@raw-input = false) {
    @propsLength: length(@props);
    @durationLength: length(@duration);
    @delayLength: length(@delay);
    @timingLength: length(@timing);
    .buildString(@i, @s: ~'') when (@i <= @propsLength) {
      @prop: extract(@props, @i);
      .setDuration() when (@i <= @durationLength) {
        @dur: extract(@duration, @i);
      }
      .setDuration() when (@i > @durationLength) {
        @dur: extract(@duration, @durationLength);
      }
      .setDuration();
      .setDelay() when (@i <= @delayLength) {
        @del: extract(@delay, @i);
      }
      .setDelay() when (@i > @delayLength) {
        @del: extract(@delay, @delayLength);
      }
      .setDelay();
      .setTiming() when (@i <= @timingLength) {
        @time: extract(@timing, @i);
      }
      .setTiming() when (@i > @timingLength) {
        @time: extract(@timing, @timingLength);
      }
      .setTiming();
      .setDivider() when (@i > 1) {
        @divider: ~'@{s},';
      }
      .setDivider() when (@i = 1) {
        @divider: ~'';
      }
      .setDivider();
      @string: @divider @prop @dur @del @time;
      .buildString((@i + 1), @string);  
    }
    .buildString(1);
    .buildString(@i, @s: ~'') when (@i > @propsLength) {
      .compact(@s);
    }
  }
  .output() when not (@raw-input = false) {
    .compact(@raw-input);
  }
  .compact(@string) {
    -webkit-transition:@string; 
       -moz-transition:@string;
        -ms-transition:@string;
         -o-transition:@string; 
            transition:@string;    
  }
  .output();
}
于 2013-12-28T02:40:56.777 回答
5

从 less.js 1.3 开始，您必须在参数列表中指定 ... 以表示可以添加更多参数。例如

.transition-property(...) {
 foo: @arguments;
}
于 2012-05-02T11:35:24.990 回答