Develop Reference

How to get checked property's value from passed control id in javascript function?

So I have this JS script:
<script>
function getCheckedProperty(obj,args)
{
if(document.getElementById("<%=checkbox1.ClientID %>").checked)
return true;
else
return false;
}
</script>
This only works for checkBox1. I want to be able to pass control id from parameters, so that it can return value of passed control. Also, please, respond with the usage.
<asp:CustomValidator runat="server" ClientValidationFunction="getCheckedProperty()></asp:CustomValidator>
TIY. SRJ.

Check this question it might have your answer.
if I get it right you want to get ids dynamically for example checkbox1, checkbox2,...
You can add the dynamic part to the id like this:
for (var i = 1; i < n; i++) {
var id = "checkbox" + i;
var ch = document.getElementById(id);
if (ch.checked == false)
return false;
}
return true;

Unfortantly, this is a real problem. The control name(s) are generated at runtime, and ALSO THIS:
document.getElementById("<%=checkbox1.ClientID %>")
So at page render time, the .net pre-processor will SWAP out the <% %> at render time.
this is also why you can't say have the js code in a external library and expect this to work.
However, your DEAD OBVIOUS question remains. Stuff a name into a simple variable and use that to get the control. After all, we can't and would not want to HARD code the value as per above, and it would be beyond silly to assume we ONLY have a means to HARD code references to controls.
So, you want of course this:
var MyControl = 'Checkbox1';
var ckBox = document.getElementById(MyControl);
if (ckBox.checked)
alert('Check box ' + MyControl + ' is checked!');
else
alert('Check box ' + MyControl + ' is UN-checked');
Now in fact the ABOVE can and will work if you force the control name generation as static.
so, here is the markup:
<asp:CheckBox ID="CheckBox1" runat="server" ClientIDMode="Static" />
So, if you ARE able and ARE willing to use ClientIDMode static, then the .net processing will NOT re-name your control. As a result you can do this:
var MyControl = 'Checkbox1';
var ckBox = document.getElementById(MyControl);
Or, even this (as HARD coded)
var ckBox = document.getElementById('CheckBox1');
Or even this:
var ckbox2 = document.getElementById(<%= CheckBox1.ClientID %>);
Now, the last one above? Well, we ARE useing the .net pre-processor to swap out the name - but it will still work - and clientID will not be changed - but the pre-processor is STILL involved.
AGAIN: the <%= 'SomeControlName.ClientID%> ONLY works because this expression is SWAPPED out at runtime by the .net web page pre-processor. This occures BEFORE the js code is run.
So you can NOT use a variable in the above <%=%> expressions since the js code HAS NOT even run and the new js code has not even been generated at this point in time.
In effect, you would (have to) do a PAGE search for the control. If you can NOT adopt ClientIdMode="static", then you MUST SEARCH the page.
You can write your OWN search routines - kind of like adopting a nice road to world poverty, or you bite the bullet, and adopt a library that WILL do the heavy lifting for you.
So, without using (forcing) StaticID on the control? then you now have to accept the BIG HUGE LARGE MASSIVE decision and introduce jQuery into your application.
jQuery is able to scour and search and look and loop and find that control for you on the web page. This is a cost not without processing cost, and not without a big speed penalty.
So, without staticID's, then you can adopt jquery and do this:
<script src="Scripts/jquery-3.5.1.js"></script>
<script>
// so if you decide and adopt jQuery, then it can do the searching for you
// BUT YOU ARE now adopting and committing to a whole new js library
// so, with jQuery we cna do this:
function jstest2(){
var ckbox2 = $('#CheckBox1');
var ckboxdom = ckbox2[0];
alert('status of check box = ' + ckboxdom.checked);
// of course the above is STILL hard code
// get control by runtime or NON hard code
// get (search) for check box based on control name in
// a variable
var MyCheckBox = 'CheckBox1';
var ckbox3 = $('#' + MyCheckBox);
var ckboxdom3 = ckbox3[0];
alert('status of check box = ' + ckboxdom3.checked);
</script>
I found after doing a nuget of jQuery, the fans on my laptop became too hot to even keep on my lap. But, things did settle down, and eventually the VS editors caught up, and things did settle down.
Also keep in mind that you have to re-learn how to reference a simple control.
eg:
<script>
function getbox() {
var tbox = document.getElementById('TextBox1');
alert(tbox.value);
// jQuery example
var tbox2 = $('#TextBox1');
alert(tbox2.val());
}
</script>
So notice now, how the long time js standard and approach is "value" as a property?
Well, now you using .val() that is a function (method) of that search result. So just keep in mind that by adopting jQuery, then all of your code that needs to get simple values from controls has to under go a syntax change, and you as a developer will have to re-lean how to reference a simple control with new syntax. The check box is a great example - it now becomes a array, and you use that array to get at the checked property.
And same in above for a simple grab of a value from a text box.
Notice how the syntax and approach to getting the value of the text box NOW has changed!!!! So you need a cheat-sheet since simple things like value now become .val().
And the same changes occur for say a label on a web page (again syntax changes).
You will ALSO notice that the results of the check box example are an array!!! So we had to drill down into the resulting array[] to get the "checked" value.
Of course how big of a deal your code changes are by adopting jQuery? Well, it depends, on relative medium sized or even a small project? $20,000 was budgeted and we still changing things.
On larger projects you simply need more manpower and would add another zero to the above cost to adopt jQuery.
However, jQuery is now widespread used, and it will do the "dirty work" of searching the DOM for you, and if you need runtime resolution as opposed to compile time resolution to find a simple control on a web page, then jQuery is probably your best choice. And I find that jQuery is really nice for ajax calls - so while it is a big change, it still well worth the effort to adopt the jQuery library and risk introducing this framework into your existing projects.

set javascript intial variable to data scraped from website

I am trying to set a variable in javascript to a value retrieved from another source. For instance, in this case, I have a calculator that is calculating estimated payments. Currently initial variables are set as follows....
// Initial Values<br>
var data; // To be used by chart<br>
var homePrice = 250000;<br>
var downPaymentPercent = 3.5;<br>
var interestRate = 5.25;<br>
var user_state = "FL";<br>
Two questions I have are...
1.) What would be the easiest way to set the interestRate variable equal to todays 'current rates' as shown by an external website such as...
www.wellsfargo.com/mortgage/rates/purchase-assumptions?prod=1
Also open to learning of a better way if there is a more straight forward method than this
2.) user_state is currently set through this initialisation list, what method would be used to set this state based on a users IP address?
My main interest is in solving question 1 right now, I am curious to question 2, but the first question is more important at the moment.
Thanks!

Convert a javascript variable to scala in play framework

I have some variables in javascript:
var something = 1;
var url = "#CSRF(routes.Some.thing(something))";
I get an error during compilation because "something" does not refer to the javascript variable, in other words; the compiler can't identify it. Is it possible to convert/inject the javascript variable somehow? Also, does this work in real time in javascript or do I need to prepare an "#CSRF(routes.Some.thing(something))" array containing each possible "something" value?
It's supposed to be a simple rest call, seen in routes file:
/something/:something controllers.Some.thing(something : Long)
An alternative would be to use a form, but I want to try not to.

You need to use a Javascript Routing and add the CSRF token to the request.
Javascript Rounting description: https://www.playframework.com/documentation/2.6.x/ScalaJavascriptRouting
Look at my answer to the question with explanation how to use it for assets("Correct and long solution"), the usage for other activities is the same: How to update src of a img from javascript in a play framework project?
So in your case, the Javascript routes generation can look like:
JavaScriptReverseRouter("jsRoutes")(
routes.javascript.Some.thing
)
And in the JavaScript:
var something = 1;
var url = jsRoutes.controllers.Some.thing(something).url;
The last - do not forget to add Csrf-Token header to the request.

Passing a javascript variable on to the next page WITHOUT server-side interference?

I'm making a web-app with PhoneGap. Here's my current hurdle:
On page one, the user chooses a latitude and longitude, then hits continue. With some nice GET action on the form and a javascript URL parser on the next page, the next page thus is passed the lat and lng coordinates. On this new page, the user is asked to input a radius. Via the same method, the radius is passed on to the final page, which displays a google map with a circle on it made from the coordinates and the radius.
But the problem is that when I pass the radius on to the final page, it obviously only passes the radius. How can I pass the lat and lng onwards from the second page, which aren't part of form information? They're already established. I know the obvious solution is to put all three variables on one page, but for foolish reasons beyond my control it needs to be this way.
So the question stands: how do you pass information that exists as a variable in javascript on to the next page? It's not part of a form. Just a variable.

All you need to do is add a couple hidden input elements to the form (<input type="hidden" />).
This can be done many ways. The shortest is to use a library (example code happens to be jQuery):
$('<input type="hidden" name="lat" />').val(latitudeValue).appendTo(formSelector);
$('<input type="hidden" name="lng" />').val(longitudeValue).appendTo(formSelector);
Raw JS is a bit longer, but not particularly complicated:
//I haven't checked this, so some cross-browser tweaking might be necessary
var lat,
lng,
form;
lat = document.createElement('input');
lat.type = 'hidden';
lat.value = latitudeValue;
lng = document.createElement('input');
lng.type = 'hidden';
lng.value = longitudeValue;
form = document.querySelector(formSelector);
form.appendChild(lat);
form.appendChild(lng);
latitudeValue, longitudeValue, and formSelector are variables that you'd have to define in the context of your page. You might also use a different parameter name, such as name="longitude".
It sounds like you really should be using AJAX to change the content of the page, so that you're not making consecutive GET requests. Instead, you could simply be swapping out the main content of the page depending on which step in the process the user is on. It would remove the necessity to do any URL parsing (which is easy to do incorrectly).

You can access get data in Javascript. Hence, just pass your data into the next page as get data in the URL and parse it as follows with Javascript.
Where your URL contains ?foo=1&bar=2 at the end, you can parse foo and bar with
var parts = window.location.search.substr(1).split("&");
var $_GET = {};
for (var i = 0; i < parts.length; i++) {
var temp = parts[i].split("=");
$_GET[decodeURIComponent(temp[0])] = decodeURIComponent(temp[1]);
}
alert($_GET['foo']); // 1
alert($_GET.bar); // 2

Easier option would be to create a cookie using Javascript/jQuery and add the values to it. So you can add all the values on every page and then finally retrieve the data you want, just from the cookie.
You use no server side scripting yet you get all the values you need.

How do I put SAFEARRAY (array of bytes) to HTML Hidden field

I'd like to get array of bytes from active-x component, store that in html-form input hidden field and then pass it to server via form-submit. How can I do that?
MIDL:
HRESULT Data([out, retval] SAFEARRAY(VARIANT) *pArray);
C++/ATL
STDMETHODIMP MyActiveX::get_Data(SAFEARRAY **pArray)
{
CComSafeArray<BYTE> arr;
for (int i = 0; i < 10; i++)
{
CComVariant a;
a = (BYTE)i;
arr.Add(a);
}
arr.CopyTo(pArray);
return S_OK;
}
Javascript:
$("#hiddenField").val(myActiveX.Data);
Browser tells me: type mismatch

Although I am not familiar with your exact situation, I have seen some similar situations before.
You are correct to put your data in a field using $('#hiddenField'). If you've put a name attribute on that field so that it becomes part of the HTTP submit, that part is good.
As for myActiveX.Data, I imagine that this is some sort of JavaScript object. Remember that only a string can be put into an HTML input; it does not hold binary data.
What I would do is put a breakpoint before $("#hiddenField").val(myActiveX.Data);
. Use the debugger keyword if you're not familiar with it. Run the code in your debugger and look at the structure of the value of myActiveX.Data. It probably has some sort of wrapper field.
Alternatively, if you don't have access to a good JavaScript debugger, try the following"
for(x in myActiveX.Data)
alert(x + ": " + myActiveX.Data[x]);

I'm assuming the C++ code is the server side code.
The best way to handle this is to serialise the SAFEARRAY. From there you can handle it in two ways.
Firstly, the serialisation. I've looked at MSDN and I think using LPSAFEARRAY_Marshal and LPSAFEARRAY_Unmarshal (with an optional IDispatch or IUnknown IID to specify the type, but the documentation doesn't say how it's used) or LPSAFEARRAY_UserMarshal and LPSAFEARRAY_UserUnmarshal to convert the SAFEARRAY to/from a serialised format.
Secondly, handling the data transfer.
Option 1: Save the serialised data on the server side and put a token representing the saved file into the hidden field.
Option 2: Use Hex, Base64, etc. to encode the data into a printable format and putting that data into the hidden field.
Either way, when you need to get the data back, just de-serialise it with the matching function.