A encapsulated getElementsByClassName method is recommended

As we know, native JS provides us with the getElementsByClassName method, which allows us to get a collection of nodes that contain a specified class, notice the collection, that is, this function returns an array.

function getElementsByClassName(oEle,sClass,sEle){

  if(oEle.getElementsByClassName){

    return oEle.getElementsByClassName(sClass);

  }else{

    var aEle=oEle.getElementsByTagName(sEle || '*'),

      reg=new RegExp('(^|\s)'+sClass+'($|\s)'),

      arr=[],

      i=0,

      iLen=aEle.length;
    for(; i<iLen; i++){

      if(reg.test(aEle[i].className)){

        arr.push(aEle[i]);

      }

    }

    return arr;

  }

}

Usage:

//First: select 
 for all div elements with box_box class under the document
  getElementsByClassName(document,'box_box','div')[0].style.background='yellow';
//Second: select 
 for all div elements under the document with class box-box 

  getElementsByClassName(document,'box-box','div')[0].style.background='yellow';
//Third: select all classes under the document to be box-box elements 

  getElementsByClassName(document,'box-box')[0].style.background='yellow';

OEle, sClass is required, sEle is optional.

In sClass, there is no problem to test the horizontal line or underline, for example: box-box box_box; But other special characters are more likely to cause problems, such as box$box...   Of course, you can escape special characters by yourself, such as: box\\$box...

Compatibility: pro - test ie6+