可编辑DIV在获得焦点的时候让光标处于最后

function insertHtmlAtCaret(html) {
            var sel, range;
            if (window.getSelection) {
                // IE9 and non-IE
                sel = window.getSelection();
                if (sel.getRangeAt && sel.rangeCount) {

                    range = sel.getRangeAt(0);
                    range.deleteContents();
                    // Range.createContextualFragment() would be useful here but is
                    // non-standard and not supported in all browsers (IE9, for one)
                    var el = document.createElement("div");
                    el.innerHTML = html;
                    var frag = document.createDocumentFragment(),
                        node, lastNode;
                    while ((node = el.firstChild)) {
                        lastNode = frag.appendChild(node);
                    }
                    range.insertNode(frag);
                    // Preserve the selection
                    if (lastNode) {
                        range = range.cloneRange();
                        range.setStartAfter(lastNode);
                        range.collapse(true);
                        sel.removeAllRanges();
                        sel.addRange(range);
                    }
                }
            } else if (document.selection && document.selection.type != "Control") {
                // IE < 9
                document.selection.createRange().pasteHTML(html);
            }
        }