背景：有个需求，有个输入价钱的输入框，需要输入框里一直有个元单位，但是保护不妨碍输入
<!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title></title> <script type="text/javascript" src="https://cdn.staticfile.org/jquery/1.10.2/jquery.min.js"></script> <meta charset="utf-8" /> </head> <body> <input type="text" onkeyup="press(this)" id="testinput" onfocus="press(this)" value="元" style="text-align:right;"/> <script> function press(obj) { var value = $(obj).val(); value = value.replace('元', '') + '元'; $(obj).val(value); var len = value.length; var index = len - 1;// 焦点在文本中的位置 set_text_value_position('testinput', len-1); } function set_text_value_position(obj, spos) { var tobj = document.getElementById(obj); if (spos < 0) spos = tobj.value.length; if (tobj.setSelectionRange) { //兼容火狐,谷歌 setTimeout(function () { tobj.setSelectionRange(spos, spos); tobj.focus(); } , 0); } else if (tobj.createTextRange) { //兼容IE var rng = tobj.createTextRange(); rng.move('character', spos); rng.select(); } } </script> </body> </html>