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Get reference to existing OpenSeadragon Viewer

I need to add an overlay to an existing OpenSeadragon viewer object which isn't created by my code, but elsewhere in the application.
I have got to a point where I know that the viewer has been created as I can access the various html elements that are created via jQuery. However I can't work out if there's any way to create a viewer from an existing reference.
I've tried using the id of the viewer div in:
var viewer = OpenSeadragon(id: "open-seadragon-viewer-id");
but this doesn't seem to work.
Is there any way to do this or can you only get the viewer within the code that initialised it?

Here's one crazy thought... you could monkey-patch some portion of OSD in order to grab the viewer...
var viewer;
var originalIsOpen = OpenSeadragon.Viewer.prototype.isOpen;
OpenSeadragon.Viewer.prototype.isOpen = function() {
// Now we know the viewer!
viewer = this;
// Reinstate the original, since we only need to run our version once
OpenSeadragon.Viewer.prototype.isOpen = originalIsOpen;
// Call the original
return originalIsOpen.call(this);
}
It's kind of tacky, but should work. Note this assumes there is only one viewer on the page... if there are more than one, the same principle could work but you would need to keep track of an array of viewers.
BTW, I'm using isOpen, because it's simple and it gets called every frame. Other functions could work as well.
EDIT: fixed code so we are using the prototype. I still haven't actually tested this code so there may still be bugs!

This solution does not directly answer the question, as it relies on your own code creating the OpenSeaDragon object. It is an implementation of #iangilman's mention of storing the viewer in a global variable. However others may find it useful. (Note that passing a global variable to a function requires a workaround - see Passing a global variable to a function)
The code demonstrates how to use the same OpenSeaDragon object to display different pictures.
var viewer3=null; //global variable
var newURL1='image/imageToDisplay1.png';
var newURL2='image/imageToDisplay2.png';
var elementID='myID';
//the loadScan function will display the picture using openSeaDragon and can be called as many times as you want.
loadScan("viewer3",newURL1,elementID);
loadScan("viewer3",newURL2,elementID);
//the actual function
function loadScan(theViewer,newURL,theID) {
//if object has already been created, then just change the image
if (window[theViewer]!=null) {
window[theViewer].open({
type: 'image',
url: newURL
});
} else {
//create a new OpenSeadragon object
window[theViewer] = OpenSeadragon({
prefixUrl: "/myapp/vendor/openseadragon/images/",
id: theID,
defaultZoomLevel: 1,
tileSources: {
url: newURL,
type: 'image'
}
});
}
}

An Alternative to Data Attribute in Jquery

i have a webpage where user can select one of different packages to buy from a list. Package details are coming from a database.
HTML Code
<div data-package='2346343' class="retail-package">Cost : 10$</div>
<div data-package='5465654' class="retail-package">Cost : 20$</div>
<div data-package='3455675' class="retail-package">Cost : 30$</div>
Jquery Code
$('.retail-package').on('click', function() {
$(this).addClass("selected-package");
var selectedPackage = $(this).data("package");
});
Now above code shows how we(specially i) normally select a particular thing out of a list when clicked, In this procedure, as you can see in HTML Code, i am giving out or showing the pakcageId to users i.e. anyone can do a inspect element in a browser and view or even manipulate the data-package attribute, for safety i do a server side check of selected data.
My Question
Is there a way to hide this data exposure, or is there any other cleaner way to accomplish this, because i have seen people using Angular, Webpack etc able to implement a list selection without giving out or showing any data which can be seen by inspect element feature in a browser.
Note : i am sorry if my question is too basic, if this cannot done using jquery what are other technologies which i can use ?

You may create a Map where keys are arbitrary, auto-incremented identifiers, and values are package numbers:
const idPackageMap = new Map()
// id generator: whenever you call it, "i" is incremented and returned
const id = (() => {
let i = 0
return () => ++i
})()
const addPackage = package =>
idPackageMap.set(id(), package)
addPackage(2346343)
addPackage(5465654)
addPackage(3455675)
console.log('contents: ', [...idPackageMap.entries()])
console.log('package number for id 2: ', idPackageMap.get(2))
Now, when you insert those <div> elements you may set the arbitrary identifier, and when you need to locate the actual package number is just about using Map#get: idPackageMap.get(1) (change 1 with any arbitrary identifier).

Creating .json file and storing data in javascript -- using vis.js

In my project I need to save the data to .txt or .xml or .json file. I could not find any answer from vis.js website/issues blog. It might be simple, do not know. Really helpful if anyone help me out with example code. Thank you so much in advance.
function saveData(data,callback) {
data.id = document.getElementById('node-id').value;
data.label = document.getElementById('node-label').value;
clearPopUp();
callback(data);
}

If I understand you correctly, you are looking for a way to save data and options of a graph. In my graph editor adaptation for TiddlyWiki Classic I use the following method to extract data (the full implementation can be found in the repo, see config.macros.graph.saveDataAndOptions, here's a simplified one):
config.macros.graph.saveDataAndOptions = function(network,newOptions) {
newOptions = newOptions || {};
// get nodes and edges
var nodes = network.body.data.nodes._data; // contains id, label, x,y, custom per-node options and doesn't contain options from options.nodes; presumably contains option values set when network was created, not current ones (it is so for x,y)
// no suitable getter unfortunately
var edges = network.body.data.edges._data; // map; for edges to/from? certain node use network.getConnectedNodes(id)
// network.body.data.edges._data is a hash of { id: , from: , to: }
// get node positions, options
var positions = network.getPositions(), // map
options = // get options stored previously
// merge newOptions into options
for(var nodeId in nodes) {
// nodes[nodeId].x is the initial value, positions[nodeId].x is the current one
if(positions[nodeId]) { // undefined for hidden
nodes[nodeId].x = positions[nodeId].x;
nodes[nodeId].y = positions[nodeId].y;
}
storedNode = copyObjectProperties(nodes[nodeId]);
storedNodes.push(storedNode);
}
//# do whatever you need with storedNodes, edges and options
// (pack them with JSON.stringify, store to a file etc)
};
However, while this works ok for storing data, this only helps to save options passed for storing explicitly which can be not very nice for some cases. I use this method in manipulation helpers and on dragEnd (network.on("dragEnd",this.saveToTiddlerAfterDragging), config.macros.graph.saveToTiddlerAfterDragging = function(stuff) { config.macros.graph.saveDataAndOptions(this,{ physics: false }); };). I haven't recieved any better suggestions, though.
If you need to get data and options reactively and setting such helper to handle certain edit events can't solve your problem, then I suggest wrapping nodes, edges and options as vis.DataSet and save those when needed. This is related too.
To answer the question about events/other ways to use such methods. Here's how I use them:
I save data after drag&drop moving of nodes, this is done using an event handler. Namely, I introduced
config.macros.graph.saveToTiddlerAfterDragging = function(stuff) {
config.macros.graph.saveDataAndOptions(this,{ physics: false });
};
(when drag&drop is used, physics should be switched off, otherwise coordinates won't be preserved anyway) and then I use
network.on("dragEnd",this.saveToTiddlerAfterDragging);
so that changes are saved.
As for saving after adding/editing a node/edge, I apply saving not by an event (although it's nice thinking, and you should try events of DataSet, since there's no special graph events for that). What I do is I add an elaborated hijack to the manipulation methods. Take a look at the source I've linked after the
var mSettings = options.manipulation;
line: for each manipulation method, like options.manipulation.addNode I hijack it so that its callback is hijacked to call config.macros.graph.saveDataAndOptions in the end. Here's a simplified version of what I'm doing:
var nonSaving_addNode = options.manipulation.addNode;
options.manipulation.addNode = function(data,callback) {
// hijack callback to add saving
arguments[1] = function() {
callback.apply(this,arguments); // preserve initial action
config.macros.graph.saveDataAndOptions(network); // add saving
};
nonSaving_addNode.apply(this,arguments);
}
The thing is, addNode is actually called when the add node button is clicked; though, I'm using a customized one to create a popup and apply changes once user is happy with the label they chose.

How to generate parent/child nest on client side?

I've searched through the myriad parent/child array/object/whatever questions here and elsewhere and haven't been able to solve my issue. I know this is a bit long, but I wanted to ensure I'm providing enough info to you guys.
Here's what I want to do:
I have a number of <div>-delineated items on the page with parent/child relationships, generated via php from my database
I want to use these items as the data source for a D3.js Dendrogram (a node-link tree diagram http://mbostock.github.com/d3/ex/cluster.html)
I'm storing them with left/right nested set values but also parentID values, so I can add ID, parentID, rgt, lft and depth attributes to the <div> elements, so I should have available whatever's needed to generate the parent/child relationships on the client side
For various reasons, instead of creating a JSON file on the server side to use as the data source, I need to create it on the client side based on the attributes in #3
I've had difficulty getting various suggested javascript functions to work and all the D3 examples I've found use either a preexisting JSON file or generated math-based file, not attributes of elements already on the page
Here is an example of what already works for me with the D3 Dendrogram, but it's not generated dynamically:
var tree3 =
{"sid": "1", "children": [
{"sid": "2", "children": [
{"sid": "5", "children": [
{"sid": "75"},
{"sid": "85", "children": [
{"sid": "87"}, ...
To give you an idea of where these attributes are in the DOM, I originally tried the below, but of course it doesn't generate any hierarchy:
function tree() {
var tree=[];
$("article").each(function(){
tree.push({
sid:$(this).attr("sid"),
l:$(this).attr("l"),
r:$(this).attr("r"),
pid:$(this).attr("pid")
});
});
return tree;
}
I've been messing around unsuccessfully with variants of the below to get a nested array:
function tree2() {
$("article").(function(d) {
return d.parent().attr("pid") === 0;
}, function(parent, child) {
return parent.attr("pid") === child.parent().attr("sid");
}).toArray();
}
So, I'm driving myself crazy trying to create the javascript array nested correctly, but it's dawned on me that I may not need to and that D3's data selectors and methods could be sufficient. Could you please help me with the code to:
Pull the needed attributes to generate the parent/child relationship within a D3 function ("sid" is the identifier) or, if this isn't possible,
Create the needed array or array-like object in javascript for use by D3 (still with "sid" as the identifier).
Thanks in advance.

You need to get recursive! Basically the trick is to pass the current parent in as you go, which changes the context and allows you to walk down the tree.
Update: Working fiddle.
Assuming your HTML structure is something like this:
<div sid="1" pid="">
<div sid="1.1" pid="1">
<div sid="1.1.1" pid="1.1">
</div>
</div>
</div>
You could do something like this:
var _json = {};
function addTreeNode(div, parentObj) {
var childObj = {
sid: $(div).attr("sid"),
pid: $(div).attr("pid")
}
// add this to it's parent in the JSON hierarchy
if (!parentObj.children) parentObj.children = [];
parentObj.children.push(childObj);
// keep adding for all children div's
$(div).find("div").each(function() {
addTreeNode(this, childObj);
});
}
// start at the roots, it will magically work it's way out to the leaves
$("body > div").each(function(){
addTreeNode(this, _json);
});
console.log(_json);
Note that if your tree is big enough, you will cause stack overflows, especially in IE. In that case, you'll need to switch this over from recursion to iteration. It's not as pretty that way, though.

How do I reference the local variable when creating Url.Action call?

Backstory: To specify the correct route for a jqGrid that I show on my ASP.NET MVC 3 page, I do something like so:
$('#jqgFlavors').jqGrid({
url: '#Url.Action("FlavorData", "IceCream")',
etc...
and that will produce the correct route either when running locally out of Visual Studio (where things live at something like "http://localhost:90125/IceCream" or on the deployed site where things live at something like "http://thehostsite/mydeployedsitename/IceCream".
Great. Now the issue I'm having is that I use the onSelectRow in the grid to do a master/details thing based on the selected row's flavor id value. First, I tried doing this to just get the route correct:
onSelectRow: function(theRow){
$('#flavorDetails').load('#Url.Action("Details","IceCream", new {id = 42)})');
}
So that I can pass the value 42 in as the 'id' parameter in the Details action of the IceCream controller. And that works fine, but of course I don't want to hard code the value 42, rather pull the flavor id from the grid itself. So I have tried to reference the flavorID but can't seem to get the syntax correct:
onSelectRow: function(theRow){
var grid = jQuery('#jqgFlavors');
var flavorID = grid.jqGrid('getCell', theRow, 'FlavorID');
$('#flavorDetails').load('#Url.Action("Details","IceCream", new {id = flavorID)})');
}
I'm sure you get what I'm going for here - referencing the flavorID value I extract from the grid. But what I get is a compilation error:
The name 'flavorID' does not exist in the current context.
I suspect this is really simple. How do I reference correctly that variable?

You could use the second argument of the .load() method which allows you to pass additional parameters:
var flavorID = grid.jqGrid('getCell', theRow, 'FlavorID');
$('#flavorDetails').load('#Url.Action("Details", "IceCream")', { id: flavorID });
This might probably use the following url: /IceCream/Details?id=123 instead of what you might want /IceCream/Details/123 because javascript doesn't know anything about your routes but why care? It will still map correctly to the controller action:
public ActionResult Details(int id)
{
...
}
But if you are really anal about urls and insist on having the first type of url I've seen people doing the following:
var flavorID = grid.jqGrid('getCell', theRow, 'FlavorID');
var url = '#Url.Action("Details", "IceCream", new { id = "_TOREPLACE_" })';
url = url.replace('_TOREPLACE_', flavorID);
$('#flavorDetails').load(url);
Personally I wouldn't do it but providing it just for the record.