原生JavaScript实现hasClass、addClass、removeClass、toggleClass

---

兼容IE6+，因IE6、IE7、IE8不支持Array.prototype.indexOf()和String.prototype.trim()，分别用Polyfill实现支持。
详细：
indexOf https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf
trim： https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim

由于现代浏览器都基本支持了classList，所以移动端可以直接使用classList会更方便一些，如：

<div class="foo bar" id="div"></div>
var div = document.getElementById('div');

div.classList.remove("foo");
div.classList.add("anotherclass");
div.classList.toggle("visible");

div.classList.contains("foo");   //

div.classList.add("foo","bar");  //Android4.3不支持

1. 应该避免直接使用多个参数，支持不全面。
2. SVG 和 MathML 元素支持度也不全面（这个坑下面的代码并未填上，请熟知，有兴趣的可以查下Zepto是怎么填坑的）。
   classList支持明细： http://caniuse.com/#search=classList

代码

Polyfill

// 让低版本IE支持 Array.prototype.indexOf
// Polyfill (indexOf @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf)
  if (!Array.prototype.indexOf) {
    Array.prototype.indexOf = function(searchElement, fromIndex) {

      var k;
      if (this == null) {
        throw new TypeError('"this" is null or not defined');
      }

      var o = Object(this);
      var len = o.length >>> 0;
      if (len === 0) {
        return -1;
      }

      var n = +fromIndex || 0;
      if (Math.abs(n) === Infinity) {
        n = 0;
      }

      if (n >= len) {
        return -1;
      }

      k = Math.max(n >= 0 ? n : len - Math.abs(n), 0);

      while (k < len) {
        if (k in o && o[k] === searchElement) {
          return k;
        }
        k++;
      }
      return -1;
    };

  }

  // 让低版本IE支持 String.prototype.trim()
  // Polyfill (trim @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim)
  if (!String.prototype.trim) {
    String.prototype.trim = function(){
      return this.replace(/^[suFEFFxA0]+|[suFEFFxA0]+$/g, '');
    };
  }

支持 classList 实现方式

function ctrlClass(opts) {
    if (!opts.ele || !opts.c) return false;
    // console.log(opts.c)
    var c = null;
    typeof (opts.c) === 'string' ? 
    c = opts.c.trim().replace(/s+/g, ' ').split(' ') :
    c = opts.c;  //修复不规范传参
    
    return opts.fun({
        ele: opts.ele,
        c: c
    });
    opts.ele = null;
}

/**
 * hasClass
 * @param (element, 'c1 c2 c3 c4 c5')
 */
 function hasClass(ele, c) {
    return ctrlClass({
        ele: ele,
        c: c,
        fun: function(opts) {
            return opts.c.every(function(v) {
                return !!opts.ele.classList.contains(v);
            });
        }
     });
 }

 /**
 * addClass
 * @param (element, 'c1 c2 c3 c4 c5')
 */
 function addClass(ele, c) {
    return ctrlClass({
        ele: ele,
        c: c,
        fun: function(opts) {
            var ele = opts.ele,
                c = opts.c;
            c.forEach(function(v) {
                if (!hasClass(ele, v)) {
                    ele.classList.add(v);
                }
            });
        }
    })
 }

 /**
  * removeClass
  * @param (element, 'c1 c2 c3')
 */
 function removeClass(ele, c) {
  ctrlClass({
    ele: ele,
    c: c,
    fun: function(opts) {
      var ele = opts.ele,
          c = opts.c;
      c.forEach(function(v) {
        // TODO 是否有必要判断 hasClass
        // if (!hasClass(ele, v)) {
          ele.classList.remove(v);
        // }
      });
    }
  });
 }


 /**
  * toggleClass
  * @param (element, 'c1 c2 c3')
 */
 function toggleClass(ele, c) {
  ctrlClass({
    ele: ele,
    c: c,
    fun: function(opts) {
      var ele = opts.ele,
          c = opts.c;
      c.forEach(function(v) {
        ele.classList.toggle(v);
      })
    }
  })
 }

不支持 classList 实现方式

/**
 * hasClass
 * @param (element, 'c1 c2 c3 c4 c5')
 */
 function hasClass(ele, c) {
    return ctrlClass({
        ele: ele,
        c: c,
        fun: function(opts) {
            var cln = opts.ele.className.split(' ');
            var c = opts.c;
            for (var i = 0; i < c.length; i++) {
                if(cln.indexOf(c[i]) !== -1){
                    return true;
                }
            }
            return false;
        }
     });
 }


 /**
  * addClass
  * @param (element, 'c1 c2 c3')
 */
 function addClass(ele, c) {
  ctrlClass({
    ele: ele,
    c: c,
    fun: function(opts) {
      var ele = opts.ele,
          c = opts.c;
      for (var i = 0; i < c.length; i++) {
        if(!hasClass(ele, c[i])) {
          ele.className = ele.className !== '' ? (ele.className + ' ' + c[i]) : c[i];
        }
      }  
    }
  });
 }


 /**
  * removeClass
  * @param (element, 'c1 c2 c3')
 */
 function removeClass(ele, c) {
  ctrlClass({
    ele: ele,
    c: c,
    fun: function(opts) {
      var ele = opts.ele,
          c = opts.c,
          cln = ele.className.split(' ');
      for (var i = 0; i < c.length; i++) {
        if (hasClass(ele, c[i])) {
          cln.splice(cln.indexOf(c[i]), 1);
        }
      }
      ele.className = cln.join(' ');
    }
  });
 }

 /**
  * toggleClass
  * @param (element, 'c1 c2 c3')
 */
 function toggleClass(ele, c){
  ctrlClass({
    ele: ele,
    c: c,
    fun: function(opts) {
      var ele = opts.ele,
          c = opts.c;
      for (var i = 0; i < c.length; i++) {
        !!hasClass(ele, c[i]) ? removeClass(ele, c[i]) : addClass(ele, c[i]);  
      }
    }
  });
 }

完整代码

// Polyfill (indexOf @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf)
if (!Array.prototype.indexOf) {
Array.prototype.indexOf = function(searchElement, fromIndex) {

  var k;
  if (this == null) {
    throw new TypeError('"this" is null or not defined');
  }

  var o = Object(this);
  var len = o.length >>> 0;
  if (len === 0) {
    return -1;
  }

  var n = +fromIndex || 0;
  if (Math.abs(n) === Infinity) {
    n = 0;
  }

  if (n >= len) {
    return -1;
  }

  k = Math.max(n >= 0 ? n : len - Math.abs(n), 0);

  while (k < len) {
    if (k in o && o[k] === searchElement) {
      return k;
    }
    k++;
  }
  return -1;
};

}


  // Polyfill (trim @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim)
  if (!String.prototype.trim) {
    String.prototype.trim = function(){
      return this.replace(/^[suFEFFxA0]+|[suFEFFxA0]+$/g, '');
    };
  }

var cl = ('classList' in document.createElement('a'));


function ctrlClass(opts) {
    if (!opts.ele || !opts.c) return false;
    // console.log(opts.c)
    var c = null;
    typeof (opts.c) === 'string' ? 
    c = opts.c.trim().replace(/s+/g, ' ').split(' ') :
    c = opts.c;  //修复不规范传参
    
    return opts.fun({
        ele: opts.ele,
        c: c
    });
    opts.ele = null;
}   

// 支持 classList
if(cl){
    /**
     * hasClass
     * @param (element, 'c1 c2 c3 c4 c5')
     */
     function hasClass(ele, c) {
        return ctrlClass({
            ele: ele,
            c: c,
            fun: function(opts) {
                return opts.c.every(function(v) {
                    return !!opts.ele.classList.contains(v);
                });
            }
         });
     }

     /**
     * addClass
     * @param (element, 'c1 c2 c3 c4 c5')
     */
     function addClass(ele, c) {
        return ctrlClass({
            ele: ele,
            c: c,
            fun: function(opts) {
                var ele = opts.ele,
                    c = opts.c;
                c.forEach(function(v) {
                    if (!hasClass(ele, v)) {
                        ele.classList.add(v);
                    }
                });
            }
        })
     }

     /**
      * removeClass
      * @param (element, 'c1 c2 c3')
     */
     function removeClass(ele, c) {
      ctrlClass({
        ele: ele,
        c: c,
        fun: function(opts) {
          var ele = opts.ele,
              c = opts.c;
          c.forEach(function(v) {
            // TODO 是否有必要判断 hasClass
            // if (!hasClass(ele, v)) {
              ele.classList.remove(v);
            // }
          });
        }
      });
     }


     /**
      * toggleClass
      * @param (element, 'c1 c2 c3')
     */
     function toggleClass(ele, c) {
      ctrlClass({
        ele: ele,
        c: c,
        fun: function(opts) {
          var ele = opts.ele,
              c = opts.c;
          c.forEach(function(v) {
            ele.classList.toggle(v);
          })
        }
      })
     }




}else{
    /**
     * hasClass
     * @param (element, 'c1 c2 c3 c4 c5')
     */
     function hasClass(ele, c) {
        return ctrlClass({
            ele: ele,
            c: c,
            fun: function(opts) {
                var cln = opts.ele.className.split(' ');
                var c = opts.c;
                for (var i = 0; i < c.length; i++) {
                    if(cln.indexOf(c[i]) !== -1){
                        return true;
                    }
                }
                return false;
            }
         });
     }


     /**
      * addClass
      * @param (element, 'c1 c2 c3')
     */
     function addClass(ele, c) {
      ctrlClass({
        ele: ele,
        c: c,
        fun: function(opts) {
          var ele = opts.ele,
              c = opts.c;
          for (var i = 0; i < c.length; i++) {
            if(!hasClass(ele, c[i])) {
              ele.className = ele.className !== '' ? (ele.className + ' ' + c[i]) : c[i];
            }
          }  
        }
      });
     }


     /**
      * removeClass
      * @param (element, 'c1 c2 c3')
     */
     function removeClass(ele, c) {
      ctrlClass({
        ele: ele,
        c: c,
        fun: function(opts) {
          var ele = opts.ele,
              c = opts.c,
              cln = ele.className.split(' ');
          for (var i = 0; i < c.length; i++) {
            if (hasClass(ele, c[i])) {
              cln.splice(cln.indexOf(c[i]), 1);
            }
          }
          ele.className = cln.join(' ');
        }
      });
     }

     /**
      * toggleClass
      * @param (element, 'c1 c2 c3')
     */
     function toggleClass(ele, c){
      ctrlClass({
        ele: ele,
        c: c,
        fun: function(opts) {
          var ele = opts.ele,
              c = opts.c;
          for (var i = 0; i < c.length; i++) {
            !!hasClass(ele, c[i]) ? removeClass(ele, c[i]) : addClass(ele, c[i]);  
          }
        }
      });
     }
}

使用

var ele = document.getElementById('test');
hasClass(ele, 'c1');
addClass(ele, 'c1 c2 c3');
removeClass(ele, 'c1 c2 c3');
toggleClass(ele, 'c1 c2 c3');

项目

https://github.com/givebest/ctrl-cssClass