how to get variable value in javascript

Question

I have script in aspx page so I want that variable value in another JavaScript file.

function ValidateStartDate() 
{
   var txtDate = document.getElementById('<%=txtDateFilterActv.ClientID  %>');
   var lastdate = txtDate.value;
}

After click on save button I want 'lastdate' variable value in another JavaScript file. How can I access it?

Answer 1

txtDate.value is correct? you can easy test it with "alert(txtDate.value);" if it is correct you declare var lastdate outside the function (global) and then you can read in other javascript function. bye. example:

var lastdate;
function ValidateStartDate() 
{
   var txtDate = document.getElementById('<%=txtDateFilterActv.ClientID  %>');
   lastdate = txtDate.value;
}

Answer 2

Say you have two files:

<script src="/test1.js"></script>

<script src="/test2.js"></script>

You could then change test1.js to:

var global = {};
global.settings = {
    valid_start_date: ValidateStartDate
  };

And then from test2.js you could use global like a scoped variable:

console.log(global.settings.valid_start_date);

Answer 3

try this

var lastdate;
var ValidateStartDate = function(){
   var txtDate = document.getElementById('<%=txtDateFilterActv.ClientID  %>');
   var lastdate = txtDate.value;
   return lastdate;
}
lastdate = ValidateStartDate();
alert(lastdate);