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setting a variable in javascript to be used in another form

I have form with a Grid (telerik), i think the technology behind it doesnt matter. I let user click on a row in the grid. During the click I extract a value from the Grid with Javascript, like so:
function RadDrillDoubleClick(sender, eventArgs) {
var Code = eventArgs.getDataKeyValue("Status");
if (Code == "In Progress" || Code == "")
{
location.href = "Main1.aspx?mode=edit&DID=" + eventArgs.getDataKeyValue("D_ID");
}
else {
location.href = "Main1.aspx?mode=view&DID=" + eventArgs.getDataKeyValue("D_ID");
}
}
After user has clicked the grid, I call this JS function and send them to correct .aspx page with either VIEW or EDIT mode dependent directly on the Code.
What I'm trying to do is once I get to the Main1.aspx page, I want to be able to continue to hold the CODE value, because when users performs a certain action, I'll need to call a javascript function and use the actual CODE to determine what the user will be able to do.....
var Code = eventArgs.getDataKeyValue("Status");
is there any way I can somehow create like a GLOBAL Variable called
CodeValue
that I can pass around to another form without doing it in the URL?

When the browser navigates to a page, all current JavaScript is unloaded from the browser. This means any functions/variables, etc. will not be accessible on the new page unless you've persisted the value in some way.
Common ways of persisting the value include:
Add it to the query string of the URL the user is navigating to
Save the value to a cookie
Save the value to local/session storage
For your scenario, #1 is probably your best bet (keep in mind the user can have multiple browsers/tabs open to your site).

One way to get the value from URL is like this: on the page Main1.aspx, you add to your JavaScript a function that will run after page loads and that will get what it needs from the current URL
var globalValue; // variable that will receive the value from URL
window.onload = function() {
var thisURL = window.location.href;
globalValue = url.split("?").pop();
// this will store in globalValue everything that comes after the last "?"
// example: if the url is www.site.com/text?value, it will store string "value" to globalValue
};

Jump to page in PDF.js with javascript

I'm trying to use PDF.js' viewer to display pdf files on a page.
I've gotten everything working, but I would like to be able to 'jump to' a specific page in the pdf. I know you can set the page with the url, but I would like to do this in javascript if it's possible.
I have noticed that there is a PDFJS object in the global scope, and it seems that I should be able to get access to things like page setting there, but it's a rather massive object. Anyone know how to do this?

You can set the page via JavaScript with:
var desiredPage = [the page you want];
PDFViewerApplication.page = desiredPage;
There is an event handler on this, and the UI will be adjusted accordingly. You may want to ensure this is not out of bounds:
function goToPage(desiredPage){
var numPages = PDFViewerApplication.pagesCount;
if((desiredPage > numPages) || (desiredPage < 1)){
return;
}
PDFViewerApplication.page = desiredPage;
}

In my case I was loading pdf file inside iframe so I had to do it in other way around.
function goToPage(desiredPage){
var frame_1 = window.frames["iframe-name"];
var frameObject = document.getElementById("iframe-id").contentWindow;
frameObject.PDFViewerApplication.page = desired page;
}

if Pdf shown into iframe and you want to navigate to page then use below code. 'docIfram' is iframe tag Id.
document.getElementById("docIframe").contentWindow.PDFViewerApplication.page=2

Html local storage saving data

I have a simple main menu program.
HOW IT WORKS:
Simple, once you click level one and click on the done button, it unlocks level two, the problem is when you refresh the page it does not save it and level two is gone again.
Code I've tried:
I tried HTML Local storage, here are some examples I used
window.highestLevel = localStorage.getItem('highestLevel');
and stuff like that but I can't get it to save the level.
Please help here is a link. jsFiddle
Note: I want to use html local storage.

Save it with
window.localStorage.setItem('highestLevel', window.higestLevel);

Make sure you check that the browser you are working with supports localstorage. You could use Modernizr or something to do that easily.
To set something in localstorage:
javascript
localStorage.setItem('your-identifier', your-data);
So for example, to save a user's name:
javascript
localStorage.setItem('username', 'Luke Skywalker');
To get "username" back from localstorage:
javascript
localStorage.getItem('username');
Hope this helps!

You'll need to use getItem (as you did in your question) when you load the page, and hide level 2 as needed:
if (localStorage.getItem("highestLevel") <= 1) {
$("#level2").hide();
}
You'll also need to setItem to save when the user gets to level 2:
function mainMenuLvl2() {
localStorage.setItem("highestLevel", 2)
$('#level2').show();
}
Here's a JSFiddle: http://jsfiddle.net/ptcbkamx/2/

You can use localStorage and sessionStorage to store your data on client side like below
localStorage.setItem("variablename","value"); //--> this value is object type anything
var storedValue = localStorage.getItem("variablename");
or
sessionStorage.setItem("variablename","value");
var storedValue = sessionStorage.getItem("variablename");

You can use:
localStorage.setItem("highestLevel", window.highestLevel);
Then, if you want to get the highest level, use this:
localStorage.getItem("highestLevel", window.highestLevel);
I hope this helped!

backbone.js and local storage with multiple browser tabs / windows overwrites data

just a very short question on using Backbone.js with LocalStorage:
I'm storing a list of things (Backbone collection) in LocalStorage. When my website is open in multiple browser windows / tabs and the user in both windows adds something to the list, one window's changes will overwrite the changes made in the other window.
If you want to try for yourself, just use the example Backbone.js Todo app:
Open http://backbonejs.org/examples/todos/index.html in two browser tabs
Add an item 'item1' in the first tab and 'item2' in the second tab
Refresh both tabs: 'item1' will disappear and you'll be left with 'item2' only
Any suggestions how to prevent this from happening, any standard way to deal with this?
Thxx

The issue is well-known concurrency lost updates problem, see Lost update in Concurrency control?.
Just for your understanding I might propose the following quick and dirty fix, file backbone-localstorage.js, Store.prototype.save:
save: function() {
// reread data right before writing
var store = localStorage.getItem(this.name);
var data = (store && JSON.parse(store)) || {};
// we may choose what is overwritten with what here
_.extend(this.data, data);
localStorage.setItem(this.name, JSON.stringify(this.data));
}
For the latest Github version of Backbone localStorage, I think this should look like this:
save: function() {
var store = this.localStorage().getItem(this.name);
var records = (store && store.split(",")) || [];
var all = _.union(records, this.records);
this.localStorage().setItem(this.name, all.join(","));
}

You may want to use sessionStorage instead.
See http://en.wikipedia.org/wiki/Web_storage#Local_and_session_storage.

Yaroslav's comment about checking for changes before persisting new ones is one solution but my suggestion would be different. Remember that localStorage is capable of firing events when it performs actions that change the data it holds. Bind to those events and have each tab listen for those changes and view re-render after it happens.
Then, when I make deletions or additions in one tab and move over to the next, it will get an event and change to reflect what happened in the other tab. There won't be weird discrepancies in what I'm seeing tab to tab.
You will want to give some thought to making sure that I don't lose something I was in the middle of adding (say I start typing a new entry for my to-do list), switch to another tab and delete something, and then come back I want to see the entry disappear but my partially typed new item should still be available for me.

Javascript storing data

Hi I am a beginner web developer and am trying to build the interface of a simple e-commerce site as a personal project.The site has multiple pages with checkboxes.
When someone checks an element
it retrives the price of the element and
stores it in a variable.
But when I go to the next page and click on new checkboxes products the variable automaticly resets to its original state.
How can I save the value of that variable in Javascript?I am using the jQuery library.
EDIT:This is the code I've writen using sessionStorage but it still dosen't work when I move to next page the value is reseted.
How can I wright this code so that i dosen't reset on each page change.All pages on my website use the same script.
$(document).ready(function(){
var total = 0;
$('input.check').click(function(){
if($(this).attr('checked')){
var check = parseInt($(this).parent().children('span').text().substr(1 , 3));
total+=check;
sessionStorage.var_name=0 + total;
alert(sessionStorage.var_name);
}else{
var uncheck = parseInt($(this).parent().children('span').text().substr(1 , 3));
total-=uncheck;
}
})

The syntax for sessionStorage is simple, and it retains it's data until the browser window is closed. It acts exactly like any other javascript object. You can use dot-notation or square bracket notation (required for keys with spaces) to access stored values.
Storing values using sessionStorage
sessionStorage['value key'] = 'value to store';
Using stored values
alert(sessionStorage['value key']); // Alerts "value to store".

You could use localStorage to acomplish this. You'd need to set up a fallback for it, using localStorage however could be done like this:
Reading from storage:
if (localStorage['valueName'] !== undefined) {
input.value = localStorage['valueName'];
}
Writing to storage:
localStorage['valueName'] = input.value;
Here's a jsfiddle example: http://jsfiddle.net/yJjLe/

As already mentioned above you can use sessionStorage or localStorage. Another option available is HTML5 Web Databases
And take a look at this presentation.
Also keep in mind that html5 web storage is not secure as anyone can see your stored data simply from the console.