为什么会出现此Javascript错误”未定义连接”？

Why am I getting this Javascript error “connection is not defined”?

我不确定为什么会出现此错误：

1 2	connection is not defined document.getElementById("flashTest").sendValFromHtml(connection.value);

这是我的代码：

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function submitCheck() {
var hasConnection = document.getElementById("formTest").connection.value.length != 0;
var hasLocation = document.getElementById("formTest").location.value.length != 0;

document.getElementById("connection").className = hasConnection ?"" :"invalid";
document.getElementById("location").className = hasLocation ?"" :"invalid";

if(hasConnection && hasLocation){
document.getElementById("flashTest").sendValFromHtml(connection.value);
}
}

HTML：

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<form id="formTest" name="formTest" method="post" action="">
<fieldset class="form">

<label id="connection">Connection:*</label>

<select name="connection">
<option value="">Select connection type</option>
<option value="dsl">DSL</option>
<option value="cable">Cable</option>
<option value="fibre">Fibre</option>
</select>

<label id="location">Location*:</label>

<select name="location">
<option value="">Select your location</option>
<option value="home">At home</option>
<option value="work">At work</option>
</select>

<label>Postcode:</label>

<input type="text" name="postcodeVal" id="postcodeVal">

<input type="button" name="sendToFlash" id="sendToFlash" value="Start Test" onclick="submitCheck();" />

</fieldset>
</form>

相关讨论

首先，将表单存储为局部变量：

1	var form = document.getElementById("formTest");

然后使用此局部变量而不是多次查询DOM：

1 2	var hasConnection = form.connection.value.length != 0; var hasLocation = form.location.value.length != 0;

最后，在connection前面加上form.：

1	document.getElementById("flashTest").sendValFromHtml(form.connection.value);

替换：

1 2	var hasConnection = document.getElementById("formTest").connection.value.length != 0; var hasLocation = document.getElementById("formTest").location.value.length != 0;

具有：

1 2	var hasConnection = document.getElementById("connection").value.length != 0; var hasLocation = document.getElementById("location").value.length != 0;