例 1.1 onblur和onfocus onblur失去焦点和onfocus得到焦点事件。 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML> <head> <meta http-equiv="content-type" content="text/html; charset=utf-8"/> <SCRIPT LANGUAGE="JavaScript"> <!-- function check(a) { var username = a.value; if (username == "") { /*String.fontcolor() (Method) Encapsulates the string within an <FONT COLOR="..."> tag context.*/ document.getElementById("error").innerHTML = "用户名不能为空！".fontcolor("red"); } } function rese() { document.getElementById("error").innerHTML = ""; } //--> </SCRIPT> </HEAD> <BODY onload="document.getElementById('u').focus()"> we can not leave the following input blank. 用户名：<INPUT id="u" TYPE="text" NAME="" onblur="check(this)" onfocus="rese()"><span id="error"></span><BR> </BODY> </HTML> 更多请见：https://blog.csdn.net/qq_43650923/article/details/100175654
