JS在光标处插入内容

$.fn.insertText = function (text) {
var obj = $(this)[0];
var range, node;
if (!obj.hasfocus) {
obj.focus();
}

if (document.selection && document.selection.createRange) {
this.focus();
document.selection.createRange().pasteHTML(text);
this.focus();
} else if (window.getSelection && window.getSelection().getRangeAt) {
range = window.getSelection().getRangeAt(0);
range.collapse(false);
node = range.createContextualFragment(text);
var c = node.lastChild;
range.insertNode(node);
if (c) {
range.setEndAfter(c);
range.setStartAfter(c)
}
var j = window.getSelection();
j.removeAllRanges();
j.addRange(range);
this.focus();
}

}