Why the css classes are not deleted in the className method in ie 9-11?

There is such a function:

function toggleClass(elem,cls,flag){ var cls1=elem.className; cls1=cls1.split(' '); var i=cls1.indexOf(cls); if ( (i >= 0 && flag > 0) || (i <0 && flag < 0)){ return; } if(flag < 0){ cls1.splice(i,1); } if(flag >= 0){ cls1.push(cls); } cls1=cls1.join(' '); elem.className=cls1; } 

the result of its multiple call in ie is as follows:

all other browsers are OK. Thanks in advance for the help) function from which the call is made:

  function scrollEffect1(){ var scroll_old = scrollEffect1.scroll_old || -1; //значение скролла var direction; //направление var scroll_new = pageYOffset; direction = scroll_new - scroll_old; var h1 = d.querySelector('h1'); var ul = d.querySelector('header ul'); if( scroll_new >=0 && scroll_new < win_size.height) { headerScroll(scroll_new, direction); toggleClass(h1, 'header-anim', direction); toggleClass(ul, 'header-anim', direction); } if ( scroll_new >= win_size.height*0.5 && scroll_new <= win_size.height) { showLeftblock(direction); showPhone('scroll',direction); } if(scroll_new >= win_size.height && scroll_new <= win_size.height*1.5){ showUp(direction); } scrollEffect1.scroll_old=scroll_new; setPosPoiner(); 

}