function showKeyCode()
{
var character = document.characterCode.character.value.substring(0,1);
var code = document.characterCode.character.value.charCodeAt(0);
var msg = "字符  \""+character+"\" 对应的ASCII码值为 "+code+".";
alert(msg);
}

document.writeln("<form name=\"characterCode\">");
document.writeln("  <center>输入一个待查字符:");
document.writeln("  <input type=\"text\" name=\"character\" size=\"15\" class=\"form\">");
document.writeln("  <input type=\"button\" value=\"显示该键值\" onClick=\"showKeyCode();\" class=\"submit\">");
document.writeln("  <\/center>");
document.writeln("<\/form>");