Use JavaScript to get the text box, Drop-down box, the value of the radio box, and assign a value

1. Text box

1.1 <input type= "text" name= "test" id= "Test" >

The value is assigned to the variable t by the Var T=document.getelementbyid ("Test").

1.2 You can, of course, assign the value of a given variable to a text box, for example:

var m = "5";

document.getElementById ("Test"). value= m;



2. Drop-down list box

2.1 <select name= "sel" id= "sel" "onchange=" Look (); " >

<option value= "1" >11</option>

<option value= "2" selected>22</option>

<option value= "3" >33</option>

</select>

with Var S=document.getelementbyid ("sel"). Value gets the value selected in <select> box, where the value= "2" option is selected by default, so the value assigned to the variable s is "2" instead of "22",

If you want to assign a "value" such as "3" ("33") to the Test text box selected in <select>, you can use the following method

<script language= "JavaScript" >

function Look () {

var se =document.getelementbyid ("sel");
var option=se.getelementsbytagname ("option");
var str = "";
for (Var i=0;i<option.length;++i)
{
if (option[i].selected)
{
document.getElementById ("Test"). Value = Option[i].text;
}
}





}

</script>

2.2 Compares the given value to the value in the <select> box, select it if <option> 's value in <select> is the same as the given value.

var m = "2",

for (var i = 0;i<document.getelementbyid ("sel"). length;i++)
{
With (document.getElementById ("sel"). Options[i])
{
if (value = = m)
{
selected = true;
}
}
}



3. Single selection box

The name attribute value must be the same for a row of a single marquee, so that the radio can be implemented.

<input type= "Radio" Name= "a" value= "1" >aaaaaaaaaa<br>
<input type= "Radio" Name= "a" value= "2" >bbbbbbbbb<br>
<input type= "button" onclick= "Check ();" value= "Test" >
<script language= "JavaScript" >
<!--
function Check ()
{
var sel = 0;
for (var i = 0; i < Document.getelementsbyname ("a"). Length; i++)
{
if (Document.getelementsbyname ("a") [i].checked)
{
sel = Document.getelementsbyname ("a") [I].value;
}
}

if (sel = 1)
{
Alert ("Aaaaaaaaaa");
}
else if (sel== 2)
{
Alert ("BBBBBBBBB");
}
}
-->
</script>

Turn from: http://www.cnblogs.com/maizitongxue/archive/2009/03/13/1410890.html