javascript - Javascript通过ID改变元素的颜色

Question

你好，我正在尝试对我正在处理的表单进行验证，我已经编写了一个函数并使用了

document.getElementById("span_trav_emer_med_insur").style.backgroundColor ='#FFFFFF';

我已经测试了显示警告消息框的功能，出于调试目的，选中“trav_emer_med_insur”时会显示消息框。我已经检查过这里和无数其他网站，他们都说 getElementById.style.backgroundColor = 'color'; 是实现我正在寻找的方法。我现在不明白为什么它不起作用，一切看起来都是正确的。

这是我的函数的开始相关部分:

function validatePlanTypes(form)    {
    var error = "";

        if (form.trav_emer_med_insur.checked)   {
            document.getElementById("span_trav_emer_med_insur").style.backgroundColor = '#FFFFFF';
            if (!form.trav_emer_med_insur_opt1.checked || !form.trav_emer_med_insur_opt2.checked || !form.trav_emer_med_insur_opt3.checked || !form.trav_emer_med_insur_opt4.checked)   {
                form.trav_emer_med_insur_opt1.style.backgroundColor = 'Yellow';
                form.trav_emer_med_insur_opt2.style.backgroundColor = 'Yellow';
                form.trav_emer_med_insur_opt3.style.backgroundColor = 'Yellow';
                form.trav_emer_med_insur_opt4.style.backgroundColor = 'Yellow';
                error = "You must pick a plan-type for Travel Emergency Medical insurance, areas with a problem have been highlighted yellow for you.";
            }

我还没有测试完整的功能，我现在只是想测试第一个 if 语句，正如我所说的 if 语句有效和 alert("bleh");如果我选中该框，将显示警报

这是我试图更改复选框周围 span 元素背景颜色的表单的 HTML。

<p><span name="span_trav_emer_med_insur" id="span_trav_emer_med_insur" value="span_trav_emer_med_insur" style=""><input type="checkbox" name="trav_emer_med_insur" id="trav_emer_med_insur_if"  value="trav_emer_med_insur_if" class="form_elements" onClick="if(this.checked){document.getElementById('trav_emer_med_options').style.display='block';}else{document.getElementById('trav_emer_med_options').style.display='none';}"/></span> <!-- Travel Emergency Medical If Box -->

                    <label class="form_elements" name="label_for_trav_emer_med_insur_if" id="label_for_trav_emer_med_insur_if">&nbsp;&nbsp;Travel Emergency Medical Insurance&nbsp;<em>(expands when checked)</em>.</label></p>
                    <p>

                    <div id="trav_emer_med_options" name="trav_emer_med_options" class="questions_hidden">

我也试过

form.span_trav_emer_med_insur.style.backgroundColor = '#FFFFFF';

同样无济于事，我真的被难住了，代码看起来和我在网上看到的一模一样。有人请告诉我我缺少什么。

谢谢，-肖恩

编辑 - 只是为了验证:

if (form.trav_emer_med_insur.checked)   {
            alert("bleh");

代替

if (form.trav_emer_med_insur.checked)   {
            document.getElementById("span_trav_emer_med_insur").style.backgroundColor = '#FFFFFF';

确实有效，所以 if 语句或函数不是问题。

在此处完成文件 - getelementbyID 不起作用 - http://hotfile.com/dl/135598683/93484d4/general2.html

使用 alert('bleh') WORKING 在此处完成文件 - http://hotfile.com/dl/135598746/dc9e14b/general23.html

工作 PHP 代码准确地显示了我正在尝试做的事情(减去页面重新加载部分):

    // Check if Emergency Medical is selected.
if (isset($_POST['trav_emer_med_insur']))   { 

    // If Emergency Medical is selected, then check to see if an option has been selected
    if (isset($_POST['trav_emer_med_insur_opt1']) or isset($_POST['trav_emer_med_insur_opt2']) or isset($_POST['trav_emer_med_insur_opt3']) or isset($_POST['trav_emer_med_insur_opt4']))   {

    $SQLString = $SQLString . "emer_med, emer_med_opt1, emer_med_opt2, emer_med_opt3, emer_med_opt4";

    }

    // If no option is selected display error message   
    else    {

        ++$ErrCount;
        $Errors[$ErrCount] = "You selected interest in Travel Emergency Medical Insurance  but did  not select a plan-type for it";

    }
}

// Check if All-Inclusive Insurance is selected.
elseif (isset($_POST['allinc_insur']))  {

    //If All-Inclusive Insurance is selected, then check to see if an option has been selected
    if (isset($_POST['allinc_insur_opt1']) or isset($_POST['allinc_insur_opt2']))   {

    }   

    //If no option is selected display error message
    else    {

        ++$ErrCount;
        $Errors[$ErrCount] = "You have selected interest in All-Inclusive Insurance but did not select a plan-type for it";

    }
}

// Check if Cancellation Insurance is selected.
elseif (isset($_POST['cancel_insur']))  {



}

// Check if Visitor Insurance is selected.
elseif (isset($_POST['visitor_insur'])) {

    //If Visitor Insurance is selected, then check to see if country is selected.
    if (isset($_POST['country_select']))    {

    }   

    // If no country selected display error message
    else    {

        ++$ErrCount;
        $Errors[$ErrCount]  = "You have selected interest in Visitor Insurance but have not selected a country";

    }       
}

//If no insurane types selected display error.
else    {

    ++$ErrCount;
    $Errors[$ErrCount] = "You haven not selected interest in any insurance plan types";

}
while ($Count != $Target)   {
    if (checked($QuestionNames[0]) != 1);
    ++$Count;
}

Answer 1

您是否尝试过从一开始就给 span 一种颜色，只是为了确认您可以看到它？

由于您的代码看起来完全没问题，所以您可能只是看不到 span 背景颜色。

就其值(value)而言，我同意 OP 的观点，即使用 jquery 处理像这样的琐碎事情是浪费带宽。

根据您的评论，我创建了一个测试页面来模拟您的评论。

这个有效:

<span name="span_trav_emer_med_insur" id="span_trav_emer_med_insur" style='backgroundcolor:red'>
some words<input type="checkbox" name="trav_emer_med_insur" id="trav_emer_med_insur_if"  value="trav_emer_med_insur_if" class="form_elements" onClick="clck(this)"/>
</span> 
<label class="form_elements" name="label_for_trav_emer_med_insur_if" id="label_for_trav_emer_med_insur_if">  Travel Emergency Medical Insurance <em>(expands when checked)</em>.</label></p>
<div id="trav_emer_med_options" name="trav_emer_med_options" class="questions_hidden" style='display:none;'>
some hidden words
</div>
<script type="text/javascript">
function clck(cbObj) {
if(cbObj.checked){
    document.getElementById("span_trav_emer_med_insur").style.background = "green";
    document.getElementById('trav_emer_med_options').style.display='block';
}
else {
    document.getElementById("span_trav_emer_med_insur").style.background = "red";
    document.getElementById('trav_emer_med_options').style.display='none';
}
}
</script>