div设置contentEditable="true"作为文本编辑器，定位光标解决办法

function set_focus(el) {
el = el[0]; // jquery 对象转dom对象
el.focus();
if ($.browser.msie) {
var rng;
el.focus();
rng = document.selection.createRange();
rng.moveStart('character', -el.innerText.length);
var text = rng.text;
for (var i = 0; i < el.innerText.length; i++) {
if (el.innerText.substring(0, i + 1) == text.substring(text.length - i - 1, text.length)) {
result = i + 1;
}
}
} else {
var range = document.createRange();
range.selectNodeContents(el);
range.collapse(false);
var sel = window.getSelection();
sel.removeAllRanges();
sel.addRange(range);
}
}