jQuery设置聚焦并使光标位置在文字最后

var editor = document.getElementById('btn');
editor.onfocus = function () {
window.setTimeout(function () {
var sel,range;
if (window.getSelection && document.createRange) {
range = document.createRange();
range.selectNodeContents(editor);
range.collapse(true);
range.setEnd(editor, editor.childNodes.length);
range.setStart(editor, editor.childNodes.length);
sel = window.getSelection();
sel.removeAllRanges();
sel.addRange(range);
} else if (document.body.createTextRange) {
range = document.body.createTextRange();
range.moveToElementText(editor);
range.collapse(true);
range.select();
}
}, 1);
}

editor.focus()