set_caret_position.js

var range = document.createRange();//Create a range (a range is a like the selection but invisible)
        range.selectNodeContents(this.target);//Select the entire contents of the element with the range
        range.setEnd(this.target.firstChild, pos);
        range.collapse();//collapse the range to the end point. false means collapse to end rather than the start
        selection = window.getSelection();//get the selection object (allows you to change selection)
        selection.removeAllRanges();//remove any selections already made
        selection.addRange(range);