html - Accessing a form variable inside javascript

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html - Accessing a form variable inside javascript

posted Jan 31, 2022 in Technique[技术] by 深蓝 (71.8m points)

html - Accessing a form variable inside javascript

I have a code like this

<html>
<head>Title
<script>
function callme()
{ 
        alert("Hi");
              document.test.action ="testAction.do";
        alert(document.getElementById("option").value);     
        alert('<%=request.getParameter("option")%>'); 
}
</script>           }
</head>
<body>
<FORM method="post" name="test" >
<select name="option" id="option">
<option>1</option>
<option>2</option>
</select>
<input type="submit" value="Submit" onClick="callme()">
</form>
</body>
</html>

This is a sample jsp code of what I have to do.The problem is I am able to get value for the document.getElementById but I want to access this parameter inside my action class which is retunring as null.Can anyone help me in solving this issue.

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1 Reply

深蓝 · Answer 1 · 2022-01-31T07:05:51+0000

Sounds a bit unclear. I presume what you are saying is that this line:

alert('<%=request.getParameter("option")%>');

shows null in the alert?

I think the main reason is that the form hasn't been submitted yet. You are using a server side "request" object, but you render this page nothing has been submitted yet hence request.getParameter("option") returns null.

If you submit this form then inside testAction.do (since this is where it will be submitted to) you will be able to read the value from request.getParameter("option")

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html - Accessing a form variable inside javascript

html - Accessing a form variable inside javascript

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