get value of a textfield onchage of another textfield (liferay aui )

Question

I have 2 input text fields in my form using one is autocomplete fields(liferay) and other is normal text fields.

Now I want to check the value of autocomplete field onchange(as in aui library we have only to events onSelect and onChange) of other normal text field.

I am trying in thsi way but still not getting any value.

<form   action="<liferay-portlet:actionURL name="saveForm"  />"
     id="<portlet:namespace />sampleForm"
    method="post"  enctype="multipart/form-data"  name="<portlet:namespace />sampleForm">
<aui:input name="firstName"  />      /* this is autocomplete field*/

<aui:input name="lastName"  onChange="myFunction()"/>
.
.
.
.

</form>

<script type="text/javascript" language="javascript">

function myFunction(){
   alert("in----------");
   alert(document.getElementByName("firstName").value());
} 

</script>

Can anybody show me a best way to get value of autocomplete field ?

Answer 1

The way you're going...

Give your elements an id as well (it can be the same as the name).

And use getElementById() instead.

Also remove () from .value()

<form   action="<liferay-portlet:actionURL name="saveForm"  />"
     id="<portlet:namespace />sampleForm"
    method="post"  enctype="multipart/form-data"  name="<portlet:namespace />sampleForm">
<aui:input name="firstName" id="firstName" />      /* this is autocomplete field*/

<aui:input name="lastName" id="lastName"  onChange="myFunction()"/>
.
.
.
.

</form>

<script type="text/javascript" language="javascript">

function myFunction(){
   alert("in----------");
   alert(document.getElementById("firstName").value);
} 

</script>