JavaScript实现输入框与清空按钮联动效果

<!DOCTYPE html><html><head><metacharset="UTF-8"><title>输入框清空按钮</title><scriptsrc="js/jquery1.8.3.min.js"></script><script>/**
* 校验当前输入框的值,如果不为空显示清空按钮
* @param element
*/functioncheckInput(element){var value = $(element).val();
if(value!=null&&''!=value)
$(element).parent().parent().children().children('.button').removeClass('none');
else
$(element).parent().parent().children().children('.button').addClass('none');
}
/**
* 清空输入框内容
* @param element
*/functionclearInput(element){
$(element).parent().parent().children().children('input').val('');
$(element).addClass('none');
}
</script><style>.none{
display: none;
}.height-20{
height:20px;;}.button{
color: red;
font-size:18px;
width:100px;
height:18px;;border:1px solid red;
border-radius:5px;
}</style></head><body><div><div><inputtype="text"placeholder="输入试试看"onkeyup="checkInput(this);" >
</div><divclass="height-20" ></div><div>
<aclass="none button"onclick="clearInput(this);" >clear input</a></div></div></body>
</html>
').addClass('pre-numbering').hide(); $(this).addClass('has-numbering').parent().append($numbering); for (i = 1; i <= lines; i++)
{ $numbering.append($('
').text(i)); }; $numbering.fadeIn(1700); }); });