如果使用bootstrap 4和SASS (+ bootstrap变量)，您可以使用以下简化的答案:

@each $breakpoint in map-keys($grid-breakpoints) {
  $infix: breakpoint-infix($breakpoint, $grid-breakpoints);

  .col#{$infix}-fifth {
    @extend %grid-column;
  }

  @include media-breakpoint-up($breakpoint, $grid-breakpoints) {
    .col#{$infix}-fifth {
      flex: 0 0 20%;
      max-width: 20%;
    }
  }
}

还支持断点，您可以简单地添加新的.col#{$infix}-xxx类

我已经为任意数量的列创建了基于bootstrap定义的SASS mixin定义(个人而言，除了12列，我使用8、10和24列):

// Extended bootstrap grid system
//
// Framework grid generation
//
// Based on Bootstrap 'bootstrap/_grid-framework.scss'. Generates classes in form of `.col-(size)-x-num` of width x/num.

@mixin make-extended-grid-columns($num-columns, $i: 1, $list: ".col-xs-#{$i}-#{$num-columns}, .col-sm-#{$i}-#{$num-columns}, .col-md-#{$i}-#{$num-columns}, .col-lg-#{$i}-#{$num-columns}") {
    @for $i from (1 + 1) through $num-columns {
        $list: "#{$list}, .col-xs-#{$i}-#{$num-columns}, .col-sm-#{$i}-#{$num-columns}, .col-md-#{$i}-#{$num-columns}, .col-lg-#{$i}-#{$num-columns}";
    }
    #{$list} {
        position: relative;
        min-height: 1px;
        padding-left:  ($grid-gutter-width / 2);
        padding-right: ($grid-gutter-width / 2);
    }
}


@mixin float-extended-grid-columns($class, $num-columns, $i: 1, $list: ".col-#{$class}-#{$i}-#{$num-columns}") {
    @for $i from (1 + 1) through $num-columns {
        $list: "#{$list}, .col-#{$class}-#{$i}-#{$num-columns}";
    }
    #{$list} {
        float: left;
    }
}


@mixin calc-extended-grid-column($index, $num-columns, $class, $type) {
    @if ($type == width) and ($index > 0) {
        .col-#{$class}-#{$index}-#{$num-columns} {
            width: percentage(($index / $num-columns));
        }
    }
    @if ($type == push) and ($index > 0) {
        .col-#{$class}-push-#{$index}-#{$num-columns} {
            left: percentage(($index / $num-columns));
        }
    }
    @if ($type == pull) and ($index > 0) {
        .col-#{$class}-pull-#{$index}-#{$num-columns} {
            right: percentage(($index / $num-columns));
        }
    }
    @if ($type == offset) and ($index > 0) {
        .col-#{$class}-offset-#{$index}-#{$num-columns} {
            margin-left: percentage(($index / $num-columns));
        }
    }
}

@mixin loop-extended-grid-columns($num-columns, $class, $type) {
    @for $i from 1 through $num-columns - 1 {
        @include calc-extended-grid-column($i, $num-columns, $class, $type);
    }
}

@mixin make-extended-grid($class, $num-columns) {
    @include float-extended-grid-columns($class, $num-columns);
    @include loop-extended-grid-columns($num-columns, $class, width);
    @include loop-extended-grid-columns($num-columns, $class, pull);
    @include loop-extended-grid-columns($num-columns, $class, push);
    @include loop-extended-grid-columns($num-columns, $class, offset);
}

你可以简单地创建类:

$possible-number-extended-grid-columns: 8, 10, 24;

@each $num-columns in $possible-number-extended-grid-columns {

  // Columns

  @include make-extended-grid-columns($num-columns);

  // Extra small grid

  @include make-extended-grid(xs, $num-columns);

  // Small grid

  @media (min-width: $screen-sm-min) {
    @include make-extended-grid(sm, $num-columns);
  }

  // Medium grid

  @media (min-width: $screen-md-min) {
    @include make-extended-grid(md, $num-columns);
  }

  // Large grid

  @media (min-width: $screen-lg-min) {
    @include make-extended-grid(lg, $num-columns);
  }

}

我希望有人会觉得它有用

为5列布局创建自定义引导下载

进入Bootstrap 2.3.2(或Bootstrap 3)自定义页面，设置以下变量(不要输入分号):

@gridColumns:           5;
@gridColumnWidth:       172px;
@gridColumnWidth1200:   210px;
@gridColumnWidth768:    128px;
@gridGutterWidth768:    21px;

下载您的构建。这个网格将适合默认的容器，(几乎)保留默认的沟槽宽度。

注意:如果你使用LESS，更新变量。而不是更少。

使用5个div，类为span2，并给第一个类为offset1。

<div class="row-fluid">
    <div class="span2 offset1"></div>
    <div class="span2"></div>
    <div class="span2"></div>
    <div class="span2"></div>
    <div class="span2"></div>
</div>

瞧! 五列等距居中。

在引导3.0中，这段代码看起来像

<div class="row">
    <div class="col-md-2 col-md-offset-1"></div>
    <div class="col-md-2"></div>
    <div class="col-md-2"></div>
    <div class="col-md-2"></div>
    <div class="col-md-2"></div>
</div>

更新

因为bootstrap 4.0默认使用Flexbox:

<div class="row">
    <div class="col"></div>
    <div class="col"></div>
    <div class="col"></div>
    <div class="col"></div>
    <div class="col"></div>
</div>

如果使用bootstrap 4和SASS (+ bootstrap变量)，您可以使用以下简化的答案:

@each $breakpoint in map-keys($grid-breakpoints) {
  $infix: breakpoint-infix($breakpoint, $grid-breakpoints);

  .col#{$infix}-fifth {
    @extend %grid-column;
  }

  @include media-breakpoint-up($breakpoint, $grid-breakpoints) {
    .col#{$infix}-fifth {
      flex: 0 0 20%;
      max-width: 20%;
    }
  }
}

还支持断点，您可以简单地添加新的.col#{$infix}-xxx类

var cols = $(".container .item").length;
if (cols == 5){
    $('div.item').removeClass('col-md-2..etc').addClass('col-md-3').css('width', '20%');
 }

Jquery和完成!框架!