javascript有个问题困扰许久，真心提问，希望大牛详细点解答！谢谢

Question

Answer 1

默认禁用，每个input blur检查是否已经输入，输入允许提交

 <style>
    div.form {text-align:center}
    div.form input{border-radius:5px;border:solid 2px #666;width:150px;margin-bottom:5px;text-align:center}
    div.form input.submit{width:200px;color:#fff;background:#666}
    div.form input.ok{background:#e4a21a;;border-color:#e4a21a}
</style>
<div class="form" id="dvForm">
    <form>
        <input placeholder="姓名" /><br />
        <input placeholder="年龄" /><br />
        <input placeholder="手机号码" /><br />
        <input type="submit" value="提交" class="submit" />
    </form>
</div>
<script src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.4.2.min.js"></script>
<script>
    $('#dvForm :text').blur(function () {
        var ok = true;
        $('#dvForm :text').each(function () { if ($.trim(this.value) == '') { ok = false; return false } });
        $(':submit', '#dvForm').attr('disabled', !ok)[ok?'addClass':'removeClass']('ok');
    }).eq(0).trigger('blur');
</script>