javascript - 如何使标签可见/不可见？

Question

我有这些日期和时间字段，我想为时间设置一个 javascript 验证。

如果格式无效，则应使标签可见，否则应不可见。

这是我目前的代码。

  <td nowrap="nowrap" align="left">
            <table border="0" cellpadding="0" cellspacing="0">
                <tr>
                    <td align="right" nowrap="nowrap">
                        <span id="startDateLabel">Start date/time: </span>
                        <input id="startDateStr" name="startDateStr" size="8" onchange="if (!formatDate(this,'USA')) {this.value = '';}" />
                        <button id="startDateCalendarTrigger">...</button>
                        <input id="startDateTime" type="text" size="8" name="startTime" value="12:00 AM" onchange="validateHHMM(this.value);"/>
                        <label id="startTimeLabel" visible="false">Time must be entered in the format HH:MM AM/PM</label>
                        <BR>
                        <span id="endDateLabel">End date/time: </span>
                        <input id="endDateStr" name="endDateStr" size="8" onchange="if (!formatDate(this,'USA')) {this.value = '';}" />
                        <button id="endDateCalendarTrigger">...</button>
                        <input id="endDateTime" type="text" size="8" name="endTime" value="12:00 AM" onchange="validateHHMM2(this.value);"/>
                        <label id="endTimeLabel" visible="false">Time must be entered in the format HH:MM AM/PM</label>
                    </td>
                </tr>
            </table>
        </td>

问题是无论我将什么设置为可见，标签都会在加载时显示。我试过 visibility = "hidden"但它仍然显示。

这是验证部分:

    <script>
function validateHHMM(inputField) {
    var isValid = /^(0?[1-9]|1[012])(:[0-5]\d) [APap][mM]$/.test(inputField.value);

    if (isValid) {
        document.getElementById("startTimeLabel").style.visibility = "hidden";
    }else {
        document.getElementById("startTimeLabel").style.visibility = "visible";
    }

    return isValid;
}
function validateHHMM2(inputField) {
    var isValid = /^(0?[1-9]|1[012])(:[0-5]\d) [APap][mM]$/.test(inputField.value);

    if (isValid) {
        document.getElementById("endTimeLabel").style.visibility = "hidden";
    }else {
        document.getElementById("endTimeLabel").style.visibility = "visible";
    }

    return isValid;
}
 </script>

那么，我应该怎么做呢？ Google 显示了不同的验证方法，但没有显示如何隐藏/显示标签

Answer 1

您正在寻找显示:

document.getElementById("endTimeLabel").style.display = 'none';
document.getElementById("endTimeLabel").style.display = 'block';

编辑:您还可以轻松地重用您的验证函数。

HTML:

<span id="startDateLabel">Start date/time: </span>
<input id="startDateStr" name="startDateStr" size="8" onchange="if (!formatDate(this,'USA')) {this.value = '';}" />
<button id="startDateCalendarTrigger">...</button>
<input id="startDateTime" type="text" size="8" name="startTime" value="12:00 AM" onchange="validateHHMM(this.value, 'startTimeLabel');"/>
<label id="startTimeLabel" class="errorMsg">Time must be entered in the format HH:MM AM/PM</label><br />

<span id="endDateLabel">End date/time: </span>
<input id="endDateStr" name="endDateStr" size="8" onchange="if (!formatDate(this,'USA')) {this.value = '';}" />
<button id="endDateCalendarTrigger">...</button>

<input id="endDateTime" type="text" size="8" name="endTime" value="12:00 AM" onchange="validateHHMM(this.value, 'endTimeLabel');"/>
<label id="endTimeLabel" class="errorMsg">Time must be entered in the format HH:MM AM/PM</label>

Javascript:

function validateHHMM(value, message) {
    var isValid = /^(0?[1-9]|1[012])(:[0-5]\d) [APap][mM]$/.test(value);

    if (isValid) {
        document.getElementById(message).style.display = "none";
    }else {
        document.getElementById(message).style.display= "inline";
    }

    return isValid;
}

Live DEMO