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Add Event Listener to Array index

I have an array that is being filled on page load by D3. I want to access that same array at another time but I still need to confirm that it has been loaded.
I don't know the propper way to do this so I just guessed a few time and I kept getting "not a function" errors
First Code (populate my svg, snapshot of current values)
d3.tsv("file.txt").then( function(data) { Loaded_Data[1]=data; document.getElementById("valve1").innerHTML = data[data.length-1]['OnOff']; //etc
});
much later, but still in a relevant timescale of async, I want to do some d3 graphing with this data, but I want to make sure that there is data in my array.
Later Code (populate graphs, weeks of data)
Loaded_Data[1].addEventListener('load', () => {console.log("success"); //d3.graphing; });
I basically want a:
while (array[1] is undefined){ Listen; }
when done => graph;
Or would it just be easier to load the entire set of documents again in another d3.tsv().then()? it seems like a waste of resources to reload the entire data. What makes this difficult is the number of sources I have to load in, and consolidating my data into one array will be (hopefully) more convenient.

just graph in the then call after you read the data:
d3.tsv("file.txt")
.then(data => graph(data)); //data is available to be used at this point
also, if I'm reading this correctly, you are listening for the array to be populated with the load event, but that is only fired when the whole page is loaded and isn't relevant to the populating of a data structure. If you need the data stored somewhere in addition to graphing, you could modify the above to:
d3.tsv("file.txt")
.then(data => {
graph(data);
myArray = data;
});

How to update d3 graphics if I load from external data?

So I haven't been able to find an example. I'm loading this huge dataset from an external file with D3, and I'm making some graph with some part of the data. When a slider is moved, I wish make the same graph with some other part of the data.
I used d3.json() for loading the data. The trouble that I'm facing is: since the d3.json() is asynchronous, it loads the dataset for once, and then I can't access it from other functions. I can't have another update function that makes a new graph since I simply can't access the data anymore.
Other people's suggestions have been "only using the data in the d3.json() function: How to store a JSON object loaded from a file?
d3.json("temp.json", function(data){
//use data here
})
// do not use data anymore
I tried to use a variable to store the data (the second answer from the same question link above):
var DATASET; // global
d3.json("file.json", function(data) {
DATASET = data;
//any other functions that depend on data
});
d3.selectAll().data(DATASET).......
And I couldn't get it to work at all, since (I assume this is the reason) the data hasn't been loaded to DATASET when the last line of d3.data calls DATASET
Is there any way I could update external data in d3? Should I just load the data again in my update function? Will it affect performance since the dataset is huge?
Thank you so much for answering!

If you want to read all the data once, you should store it in your global DATASET variable, just as you show in your code fragment. But instead of placing the update logic in your main script flow, put it inside an update(...) function, and call that from the d3.json callback, too... something like this (untested):
var DATASET; // global
d3.json("file.json", function(data) {
// data is loaded, save the full set
DATASET = data;
// filter the initial subset
var subdata = data.filter(...);
// now update the graph
updateGraph(subdata);
});
function updateGraph(data) {
// when invoked without any data, use the full dataset
var newdata = (data == null ? DATASET : data);
// data rendering logic starts here...
d3.selectAll().data(newdata);
...
}
This saves the full dataset in a global variable, draws the inital graph with a filtered subset of the data, and also allows you to change which data is shown by using a different filter before calling the function again.

Go to an anchor point in a template with code in Angular 4

I have an Angular 4 application in which I need to add the following functionality:
There is a component with a list of objects. When the user double clicks on one of them, the app retrieves from a DB a list of objects and it should scroll to where the object appears.
I'd like to know how I could move to the desired position in the data once that it has been displayed in the browser. Right now, I have the following code:
let objElement = document.querySelector("#object_"+searchItem._objectID);
if (objElement){
objElement.scrollIntoView();
console.log("****** SCROLLING TO OBJECT");
}
The problem is that, the first time that I load the data from the DB, it seems that 'document.querySelector' returns null, as if the HTML wasn't 100% constructed yet, so it doesn't scroll to the position. If I try to locate the element again, it scrolls perfectly (as it doesn't reload the data from the DB).
Is there a "more Angular" way of doing this? I'm trying to find an example like this in the Angular Router documentation but I can't find anything...
EDIT:
To make things clearer, this is the pseudo-code that I run when the user selects an object:
if(selectedObject IS IN currentLoadedObjects) {
scrollTo(selectedObject); // This function runs the code above
}
else { // The object is in a different list, so retrieve it from the DB
ObjectService.getObjectListFromDB(selectedObject)
.subscribe((returnedList) => {
displayObjectList(returnedList); // Basically, this function parses the returned data, which is displayed in the template using an *ngFor loop
scrollTo(selectedObject);
});
}
As you can see, I try to scroll to the object inside the 'subscribe' method, once that I have the data from the database and after I've parsed it. The object list is pretty big, so it takes 1-2 seconds to be displayed in the browser.
Thanks!

Continuously Add | Update | Refresh data from database to a page without post back

After a new data has been inserted into database, I want the page which is used to display the data from database to be refreshed/updated and show the new data automatically without hitting the refresh button (like in Facebook feed page, or right here in stackoverflow.com, when new answer posted, it shows an alert of that answer immediately)
What techniques I should use to archive that?

There is a function in JavaScript called setInterval that takes two arguments: a function to execute, and an interval in milliseconds with which the function is run. So, you can have a function called update that fetches all the new data and appends it to your tables, and pass it to setInterval to continuously execute. To run an update function every 5 seconds, you can do something like this:
function update() {
//fetch new data using AJAX and update tables
}
setInterval(update, 5000);

For make the page add new row to waiting customer table automatically
You have to make an ajax call in every few seconds to check whether any new row added if yes then you have to fetch that row and append it to table.

How do I load data for Dojo Dgrid Table using AJAX?

I am exploring using DGrid for my web application. I am trying to have a table similar to this.
The code for the example above is here.
The table uses a memory store as the source of its data - the summary field there is what shows up when we click and expand each row.
I want the details(i.e the text shown when we click a row) to be fetched from the server on clicking on the row instead of being statically loaded along with rest of the page.
How do I modify the above code to be able to do that?
(My requirement is that of an HTML table, each row expandable on clicking, where the data on each expansion is fetched from the server, using AJAX for instance. I am just exploring dgrid as an option, as I get sortable columns for free with dgrid. If there is a better option, please let me know)
EDIT: Basically I am looking for ideas for doing that and not expecting anyone to actually give me the code. Being rather unfamiliar with Dojo, I am not sure what would be the right approach

If your ajax call returns html, you could place a dijit/layout/ContentPane in your renderer, and set the url of the contents you want to fetch in the ContentPane's href property. Assuming that your initial data (the equivalent of the example's memory store) would have a property called "yourServiceCallHref" containing the url you want to lazy load, your could try this :
require(["dijit/layout/ContentPane", ...], function(ContentPane){
renderers = {
...,
table: function(obj, options){
var div = put("div.collapsed", Grid.prototype.renderRow.apply(this, arguments)),
cp = new ContentPane({
href : obj.yourServiceCallHref
}),
expando = put(div, "div.expando", cp.domNode);
cp.startup();
return div;
}
});
If your service returns json, you could probably do something with dojo/request in a similar fashion. Just add your dom creation steps in your request callback and put them inside the div called "expando"...
Another option would be to replace the Memory store by a JsonRest store, and have the server output the same json format than the one you see on the Memory store. That means all the data would be fetched in a single call though...