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How to access the Asp.net Previouspage object when redirecting using javascript

Here's some background info:
Page 1: Contains a text box
Page 2: Contains a label
If I do a Response.Redirect("Page2.aspx") I can easily access the text box on Page1.aspx by using PreviousPage.TextboxRef and assign its value to the label on Page2. No problems here. Everything works as expected.
However, if I do a JS redirect like this:
window.location.href = "Page2.aspx";
The PreviousPage object on Page2 is null. I have tried writing a function that does a "post" instead, but that still results with the same issue.
I also tried checking the Request.UrlReferrer.ToString() value and it is coming back correctly as Page1.aspx.
I'm sure it's something simple, but alas; I'm a noob.
I have searched for a solution with no success, so I'm hoping someone here can help.

Here you can do something like this in javascript where you are setting url.
window.location.href = "Page2.aspx?txt1Value="+document.getElementById('txt1Value').value;
and on other page you can get it using querystring in c#
Label1.Text = Request.QueryString["txt1Value"];

Hiding Password field content from users

I'd like to know if its possible for me to do something from the following :
1) Replace the source code visible in view source , with an image , or nothing at all.
2) Hide the value attribute of <inpt type="password" ....> tag , so that the password entered by the user is not visible to anyone .
Thanks in advance.

You can minify your HTML to make it slightly unreadable, but it's trivial to unminify it. You can't do anything further to "remove" or "hide" it.
You mean to hide the value attribute after the user types something in, or to hide the value sent from the server? If the former, you could use JavaScript to extract the value as it's typed into some variable and replace the value with gibberish. If the latter, then the obvious answer is to not send that value.

View source is a representation of static HTML, so if you create any element dynamically, it will not be displayed in view source.
Note: These fields will still be accessible using dev tools.
Following is a sample code:
JSFiddle
function submit() {
var uName = document.getElementById("txtUserName").value;
var uPass = document.getElementById("txtUserPass").value;
console.log(uName, uPass);
}
function addPasswordField() {
var passInput = "<input type='password' id='txtUserPass' />";
document.getElementById("content").innerHTML += passInput;
}
(function() {
addPasswordField();
})()
<div id="content">
<input type="text" id="txtUserName">
</div>
<button onclick="submit()">submit</button>

There is no way to hide source code in a browser since that is how these things are built. The web is an open platform and developers working with the web need to have the view source functionality while working on their project(s). May I ask why you feel the need to hide the source code and the password?

To answer the first question: No. This is how browsers are designed and there are lots of other ways to request the page to see the source. For example, you could use Fiddler to see the traffic passing between the server and the browser.
As for the second question...why are you trying to hide the password?
Using the password input type will prevent anyone from seeing the password on the screen. so I assume this is to stop the data being viewed in transit?
If you want to secure your connection between the client and the server, you should consider using a secure (https) connection. Thanks to LetsEncrypt this is free, so it is no longer a costly option.

Automatically updating a PHP variable when a radio button or dropdown menu item is selected

My classmates and I are building a small submission form in which a user submits shipping and billing information for their order.
The two main factors that effect the order price are the type of shipping the user selects ( $shippingType ) and the price of the item ( $initialPrice ). The variable $totalPrice is then defined which adds $shippingPrice and $initialPrice.
What we are working towards is having $totalPrice update when $shippingPrice is changed without the user having to resubmit the form. Can this be solved using php? Or would we have to use a jquery event to update the page in realtime.

You'll want to use some sort of jQuery as mentioned above. It's important to understand that PHP is only used either in AJAX, or before the page has loaded. Meaning you cannot use PHP on a page that has already been loaded. To change elements after it's loaded you would need to use javascript/jquery of some sort. I've attached a quick fiddle to illustrate an example of what I think you're looking for.
The gist of it is that you would bind a change event so that when the elements you want to use for mathing are changed you can update the other items.
$('#shipping').bind('focus, change', function() {
//Get the inital value of the #cost input
var initial_val = parseInt($("#cost").val());
//Value from the #shipping input
var additional = parseInt($("#shipping").val());
//Parsed ints because '+' is used for concatination as well, so making the vars ints will make '+' go back to math.
$("#cost").val(initial_val + additional);
});
No it's not the prettiest, but it works.
Here's the Fiddle:
http://jsfiddle.net/Lb486ck8/2/

You will have to use Javascript to accomplish this behavior. Furthermore, you will need to use AJAX (Asynchronous Javascript And XML) to make it work. AJAX is a way for Javascript to send requests to a web page "behind the scenes" while your page stays in the foreground.
http://api.jquery.com/jQuery.post/

Non-AJAX jQuery POST request

I am trying to use the jQuery POST function but it is handling the request in AJAX style. I mean it's not actually going to the page I am telling it to go.
$("#see_comments").click(function() {
$.post(
"comments.php",
{aid: imgnum},
function (data) {
}
);
});
This function should go to comments.php page with the aid value in hand. It's posting fine but not redirecting to comments.php.
#Doug Neiner Clarification:
I have 15 links (images). I click on a link and it loads my JavaScript. The script knows what imgnum I opened. This imgnum I want in the comments.php. I have to use this JavaScript and no other means can do the trick. The JavaScript is mandatory
Your method successfully POSTs the aid value. But in the comments.php when I try to echo that value, it displays nothing.
I am using Firebug. In the Console, it shows the echo REQUEST I made in Step (2) successfully.

I know what you are trying to do, but its not what you want.
First, unless you are changing data on the server, don't use a POST request. Just have #see_comments be a normal <a href='/comments.php?aid=1'>...
If you have to use POST, then do this to get the page to follow your call:
$("#see_comments").click(function() {
$('<form action="comments.php" method="POST">' +
'<input type="hidden" name="aid" value="' + imgnum + '">' +
'</form>').submit();
});
How this would actually work.
First $.post is only an AJAX method and cannot be used to do a traditional form submit like you are describing. So, to be able to post a value and navigate to the new page, we need to simulate a form post.
So the flow is as follows:
You click on the image, and your JS code gets the imgnum
Next, someone clicks on #see_comments
We create a temporary form with the imgnum value in it as a hidden field
We submit that form, which posts the value and loads the comments.php page
Your comments.php page will have access to the posted variable (i.e. in PHP it would be $_POST['aid'])

$("#see_comments").click(function () {
$('<form action="comments.php" method="POST"/>')
.append($('<input type="hidden" name="aid">').val(imgnum))
.appendTo($(document.body)) //it has to be added somewhere into the <body>
.submit();
});

While the solution by Doug Neiner is not only correct but also the most comprehensively explained one, it has one big problem: it seems to only work at Chrome.
I fidgeted around for a while trying to determine a workaround, and then stumbled upon the second answer by devside. The only difference is the extra code appendTo($(document.body)). Then I tested it in firefox and it worked like a charm. Apparently, Firefox and IE need to have the temporary form attached somewhere in the DOM Body.
I had to do this implementation for a Symfony2 project, since the path generator inside the .twig templates would only work with GET parameters and messing with the query string was breaking havoc with the security of the app. (BTW, if anyone knows a way to get .twig templates to call pages with POST parameters, please let me know in the comments).

i think what you're asking is to get to 'comments.php' and posting aid with value imgnum. The only way to do this is to submit this value with a form.
However, you can make this form hidden, and submit it on an arbitrary click somewhere with jquery.
html necessary (put anywhere on page):
<form id='see_comments_form' action='comments.php' action='POST'>
<input id='see_comments_aid' type='hidden' name='aid' value=''>
</form>
js necessary:
$("#see_comments").click(function(){
$('#see_comments_aid').val(imgnum);
$('#see_comments_form').submit();
);
this will redirect to 'comments.php' and send the proper value imgnum (that i assume you are getting from somewhere else).

Actually, $.post() sends some data to the server. It does not cause any redirection unless you do it in your server side code which handles the POST request. I can suggest two solutions:
To go to comment page, instead of using JQuery post, you can simply use a 'anchor' tag - Show Comments.
Or if you are want to go through JQuery, you can use this code snippet: $(location).attr("href", "comments.php?aid=1");

didnt exactly solve the problem. but did manage to work around it. i had to do a lot modification to the JS to make this work, but the core problem of this question was solved by doing this:
$("#see_comments").attr({href: "comments.php?aid='"+imgnum+"'"});
this appended the aid value to the URL as #Doug Neiner initially suggested me to do.
Thanks a lot Doug for all the effort. I really appreciate. +1 and accept to your answer for the effort.

Calling a javascript file (.js) via Excel VBA?

How to call a javascript file (.js) via Excel VBA?
So as i am opposed to the same kind of problem i'll try to submit you guys my case.
I am trying to automate datas extraction from valeo's catalogue using excel vba macro.
I have a list of références attached to valeo's automotive products (huge list, as more than 3000 thousands items). And i would like to import directly informations from the catalogue wich seems to run under javascript.
The datas i need is the list of every vehicules attached to a reference.
Here is the url: http://outcat-cs.tecdoc.net/ows/en/7FA2A0C501BC34CA4BECB04095663CF1.ows_cs2.srv?view=VIndexFramesetJsp
I'd like to access to the "Direct Article Search" tab, in order to copy a reference directly from an excel tab's cell and then simulate a clic on the reference in order to display the "linked vehicules section" and then to copy them in a new excel sheet.
I already succeede in doing this with html pure programmed webpage (oscaro.com) using the following code :
Set maPageHtml = IE.document
Set Helem = maPageHtml.getElementsByTagName("input")
For i = 0 To Helem.Length - 1
If Helem(i).getAttribute("name") = "toFind" Then Helem(i).Value = "819971" '819971 is the valeo reference searched
If Helem(i).getAttribute("name") = "submit" Then Set Monbouton = Helem(i)
Next
Monbouton.Click 'this does the click on my button Monbouton
But this technique can't be used with valeo website since I am not able (or at least I don't know yet how to do it) to select/click a button when the page is made on javascript, since it doesn't have a name, value or id for the button.
Also it seems that the url in the address field is the same before clicking on the "Direct Article Search" button and after having clicked....
Hope i am clear enought in spite of my english...
Greetings

All the previously suggested approaches sound hacky to me.
For a more reliable solution, embed the Javascript in a COM component via Windows Script Components, and call the Javascript-based COM component as you would any other COM component.

I don't think that there is a direct way to run JavaScript code in VBA.
What you could try to do is to embed the JavaScript code in an HTML form which you could open in a (hidden) browser control. Then fill the form controls via the DOM of the browser control and submit the form. The submit triggers the JavaScript function that you want to call.
Sample (not tested):
VBA:
oIE.Document.frmMain.param1.Value = 5
oIE.Document.frmMain.param2.Value = "6"
oIE.Document.frmMain.submit.click ' this line will call the JavaScript function
HTML:
<div id="submit" > Do Action</div>
<script>
function doAction()
{
// do whatever the code should do
}
</script>

You mean through windows scripting host?
You can shell (use the shell command) out to wscript.exe with the name of the .js file.
But this javascript object model won't be like the one you get in the browser.
It would be helpful if you told us what the javascript was supposed to do.