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How do I send user to a link upon successful xhr POST?

I have a working web page, complete with a JavaScript function that displays text messages based on the "non-successful" results, within the same page. Everything is working except this last step.
I need to send a JSON string to my server in a POST, and regardless of outcome, I need the user's browser to navigate to the page returned in the POST. (Just as if it were an ordinary link ( href ="" type of thing.) I am using the custom tag [OK_RESULT_URL] that my server replaces with the real URL just before the page is downloaded.
You see in my code below, that I set the URL to [OK_RESULT_URL] AND the window.location to [OK_RESULT_URL] as well, which seems wrong. That means I'm making two hits to [OK_RESULT_URL], one is a POST with a body (which is correct) and the other one a GET without a body (which is wrong).
I'm a total newbie to JavaScript, so I'm probably missing something obvious. It's as if instead of using xhr.Send() I want to say xhr.SendAndNaviateTo() ... or something like that.
Thanks for any help you can provide.
onApproval: function (response) {
showResult("Approved", JSON.stringify(response, null, ''\t''));
let xhr = new XMLHttpRequest();
let url = "[OK_RESULT_URL]";
xhr.open("POST", url, true);
xhr.setRequestHeader("Content-Type", "application/json");
xhr.onreadystatechange = function () {if (xhr.readyState === 4 && xhr.status === 200){
window.location = "[OK_RESULT_URL]"};
var data = JSON.stringify(response);
xhr.send(data);
}

How can I stop caching when using AJAX to read a file?

I'm currently building a website that uses AJAX to dynamically update sections of the page without the need to refresh, however, when I change aspects of the file that AJAX reads the website sometimes takes minutes to update even though the file is read about once per second. Whilst looking for the issue I found that I can turn caching off by using the developer tools and this then allowed the website to update at the appropriate speed.
Here's the code I am using:
var path = "Path of the json file i am reading"
var state;
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
state = JSON.parse(this.responseText);
}
};
xhttp.open("GET", path, true);
xhttp.send();
I've been looking for a while now and the only advice I can see about what to do about the cache is to use the developer tools to turn it off. Is there any way I can implement some code to automatically tell the browser to not cache the file being read?

How to reload the CSS or button or part of a page after get request is received?

after get request arrive the values are there and the button disappear
this is the button working on the localhost..
Im trying to add a Facebook share button in a page with dynamic contents like userid, coming from a esp826 server, using java script like innerhtml by ajax call get request once of json when the page body is on-load. When i test in my local host everything is ok since the json file load very fast and before the button loads and so everything works ok. but when i use the esp8266 server the response of the get request come somewhat after the button is loaded and so when it received and the fields get populated with the values the button disappear and remain only a word with a link.
basically the button is working on my localhost... so the innerhtml and everything is ok.. it seems i need to find a way to reload the css or something by the javascript to get the button box alive again.
is there a way to reload the button?
the .json file is just this: getajx.json
{"temp1":"1", "energia":"2", "energiatotal":"3", "tem":"2", "cliente":"22", "usuario":"22"}
you can test on your localhost by placing this getajx.json file having that content in the same directory of the html page is going to work... but i need to know how to make it work if the get request get too long.. please any help???
i tried to add a flag after the response is positive and activate the reloadCss funtion with it but didnt worked
<script>
var temp1, energia, energiatotal, tem, cliente, usuario ;
var ok=0;
function GetAjx() {
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
ok = 1;
var myObj = JSON.parse(this.responseText);
document.getElementById("temp1").innerHTML = myObj.temp1;
document.getElementById("energiatotal").innerHTML = myObj.energiatotal;
document.getElementById("tem").innerHTML = myObj.tem;
}};
if (ok =1) { function reloadCss(){
var links = document.getElementsByTagName("link");
for (var cl in links){
var link = links[cl];
if (link.rel === "stylesheet")
link.href += "";
}}
};
xmlhttp.open("GET", "getajx.json" , true);
xmlhttp.send();
}
</script>

I found a solution...
apparently i had to change the order of the scripts making the jquery ajax source load first and also tried to put the script from facebook at the bottom of the page...
i took away the reload scripts and other facebook scripts i was testing
and most importantly made the get request false to make it sync instead of async this forces the page to wait for the get request finish..strangely i tried it before and didnt worked this solution perhaps because of the order of the scripts.. can anyone comment on that?
xmlhttp.open("GET", "getajx.json" , false);
was helpful using the f12 on google chrome in specific the performance tab
i decided to not mess up with priority of the scripts even if i tried
any comments i would appreciate
again
thanks for the help

Get text from a link in javascript

I am trying to get text from a service on the same server as my webserver. The link is something like this:
http://<OwnIPadres>:8080/calc/something?var=that
This is my code:
function httpGet(theUrl)
{
alert(theUrl);
var doc = new XMLHttpRequest();
doc.onreadystatechange = function() {
if (doc.readyState == XMLHttpRequest.DONE) {
alert("text: " + doc.responseText );
document.getElementById('ctm').text = doc.responseText;
}
}
doc.open("get", theUrl);
doc.setRequestHeader("Content-Encoding", "UTF-8");
doc.send();
}
The url that i print in my first alert is the good one if i test in my browser, it is an html page with a table in it. But the alert of my text is empty? Is it a problem that the text is html?

Actually, its quite ok that your 'text' is 'html'. The problem is that using a different port counts as cross-site scripting. Therefore, your XMLHttpRequest is being stopped by the browser before it actually reaches your page across port 8080.
I'm not sure what else you're doing before and around this code snippet, but you could try an iframe call to your url to get your data, or you could add an
Access-Control-Allow-Origin: http://:8080/
in your header (however that will only get you the most modern browsers).
Finally, you could pull in a JS framework like JQuery which could help you with pulling in this service data.

Ajax call from Bookmarklet

I am trying to create a bookmarklet that, upon clicking, would request some information from the user (a url and a couple other fields in this case) and then send that data to a php page on my server and then display the result.
I would like to do an Ajax call for this so that I don't actually redirect to the new page, just get the data but I assume I would run into the "Same Origin Policy" limitation of Ajax.... is there any known way of basically doing the same thing?
Also, what would be the best way to pass the parameters? I already have a mechanism in place to recieve the parameters as a post message from a form...is there any way I could just reuse this?

You can set a bookmarklet by create a bookmark and add that piece of code below in location, but, according to same origin policy limitation, that will only work when the current tab is on the same location, here www.google.com.
If I've understand well your needs, that should be ok for your problem.
var request = new XMLHttpRequest();
request.open("GET", "http://www.google.com", true);
request.onreadystatechange = function() {
var done = 4, ok = 200;
if (request.readyState == done && request.status == ok) {
if (request.responseText) {
alert(request.responseText);
}
}
};
request.send(null);
I don't know if POST would work.

You won't be able to do a post, but a GET will work fine. If you're using something like jQuery, it will simply create a script tag with a src URL which would send the data you are looking to submit.
You will have to return JSON style data.
See: http://docs.jquery.com/Ajax/jQuery.getJSON
Alternatively, your bookmarklet could create an iframe on the page, and that could do you work of submitting the data (you could use post then) if you weren't looking to communicate between the iframe and the page itself, but instead just use user input to submit.