I know this may not be the best way but it works.

Here is what I did -

#scrollableDiv {

    position:fixed;

    top:50px;

    width:300px;

    height:500px;

    word-wrap: break-word;

    overflow-y: scroll; 

}



document.getElementById(scrollableDiv).innerHTML = longText;

document.getElementById(scrollableDiv).scrollTop = 0;