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!

这个很棒:http://www.ianmccullough.net/5-column-bootstrap-layout/

只做:

<div class="col-xs-2 col-xs-15">

和CSS:

.col-xs-15{
    width:20%;
}

在我看来，像这样使用Less语法更好。 这个答案是基于@fizzix的回答

这样列使用用户可能覆盖的变量(@grid-gutter-width, media breakpoints)， 5列的行为与12列网格的行为匹配。

/*
 * Special grid for ten columns, 
 * using its own scope 
 * so it does not interfere with the rest of the code
 */

& {
    @import (multiple) "../bootstrap-3.2.0/less/variables.less";
    @grid-columns: 5;
    @import  (multiple) "../bootstrap-3.2.0/less/mixins.less";

    @column: 1;
    .col-xs-5ths {
        .make-xs-column(@column);
    }

    .col-sm-5ths {
        .make-sm-column(@column);
    }

    .col-md-5ths {
        .make-md-column(@column);
    }

    .col-lg-5ths {
        .make-lg-column(@column);
    }
}

/***************************************/
/* Using default bootstrap now
/***************************************/

@import  (multiple) "../bootstrap-3.2.0/less/variables.less";
@import  (multiple) "../bootstrap-3.2.0/less/mixins.less";

/* ... your normal less definitions */

.col-half-offset{
    margin-left:4.166666667% !important;
    float: left;
}

<div className="row1 marginTop20">
    <div className="col-xs-12 col-sm-2 col-md-2">
        1
    </div>
    <div className="col-xs-12 col-sm-2 col-md-2 col-half-offset">
        2
    </div>
    <div className="col-xs-12 col-sm-2 col-md-2 col-half-offset">
        3
    </div>
    <div className="col-xs-12 col-sm-2 col-md-2 col-half-offset">
        4
    </div>
    <div className="col-xs-12 col-sm-2 col-md-2 col-half-offset">
        5
    </div>
    <div className="clearfix"></div>
</div>

Bootstrap默认可以缩放到12列?这意味着如果我们想要创建一个宽度相同的12列布局，我们将在div class="col-md-1"中写入12次。

<div class="row">
<div class="col-md-1"></div>    
<div class="col-md-2">1</div>
<div class="col-md-2">2</div>
<div class="col-md-2">3</div>
<div class="col-md-2">4</div>
<div class="col-md-2">5</div>
<div class="col-md-1"></div>
</div>

在bootstrap v4.3.1中，它是一个12 / 5 = 2.4列宽的列。我们称它为col-2dot4(以及col-sm-2dot4, col-md-2dot4，…)

每一列应该有20%的可用空间。

SCSS代码如下所示:

@mixin make-5-grid-column($columns: $grid-columns, $gutter: $grid-gutter-width, $breakpoints: $grid-breakpoints) {

  // Common properties for all breakpoints
  %grid-column {
    position: relative;
    width: 100%;
    padding-right: $gutter / 2;
    padding-left: $gutter / 2;
  }

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

    .col#{$infix}-2dot4 {
      @extend %grid-column;
    }

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

    @include media-breakpoint-up($breakpoint, $breakpoints) {

      // Provide basic `.col-{bp}` classes for equal-width flexbox columns
      .col#{$infix} {
        flex-basis: 0;
        flex-grow: 1;
        max-width: 100%;
      }

      .col#{$infix}-auto {
        flex: 0 0 auto;
        width: auto;
        max-width: 100%; // Reset earlier grid tiers
      }


      .col#{$infix}-2dot4 {
        @include make-col(1, 5);
      }
    }
  }
}

@if $enable-grid-classes {
  @include make-5-grid-column();
}