textbox

Hi, first I’m not js programmer…but I need a bit of help.

There is a textbox vaguely defined like this:
SEMrush

<input class=”somerandomname” value=””>

By typing text or using paste(from clipboard) element value, in the source code, visibly changes from empty one to match entered text.
However when I try to use javascript to populate the textbox, although the text do visually appears inside,
value is not changed, like in previous case, and the textbox is treated as empty.

Is there something I can do to properly fill the box by use of js?