Perform window.location.replace multiple times in for loop - javascript

I'm not able to get my script to run window.location.replace multiple times. I have a flask application that create files given the unique ids found from streaming access logs on the server. Once the file is on the server, I have a flask route that if the user is redirected to https://somewebsite.com/getFile/<id>, it will than push the file that was created on the server to the client.
Here's my script below:
<script>
var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function(){
var response = '';
if(xhr.readyState === 4 && xhr.status === 200){
response = xhr.responseText;
response = response.substring(0, response.length-1);
response = response.split('\n');
for(x in response){
url_path = response[x];
window.location.replace(url_path);
};
};
};
xhr.open('GET', '{{ url_for('stream') }}', true);
xhr.send();
</script>
I did a few console.log() calls to see if the for loop is running correctly and it is. Even the url_path given to window.location.replace is correct. One thing to note is that when being redirecting to https://somewebsite.com/getFile/<id>, the browser doesn't technically change to that url path, because flask isn't rendering a template, but instead returning a download file, so the browser stays at the current url path after the file is downloaded.
I'm not sure why I am not able to get the script to run window.location.replace more than once. It seems like if there's 2 url_path in the response object, only the last one is being downloaded. Same goes with 3 or 4 paths. Any insight would be helpful. Thanks

An alternative solution I just figured out was instead of redirecting the same browser to multiple urls, why not just open them up in different tabs. I did this by using window.open, which to my surprise did work.
However, my browser pop up blocker did block them out at first, but after changing the settings and allowing pop ups for the page, I was successfully able to have multiple files downloaded to the client. Also, since there's no template rendering on the server side, the tabs themselves don't actually pop up, so the browser won't be flooded with tabs.
I'm still interested in knowing why window.location.replace didn't work if anyone knows why.

Your code is not working because what window.location.replace does is to literally replace the source document (see documentation) with the one provided by the new URL.
What this means is that any code you put after window.location.replace won't be executed.
That is why window.open works perfectly for your situation, because it will open a new document apart from the one it is called. But be careful because not all parameters work for all browsers (check this for compatibility specifications).

Related

Page loading takes time

My website uses ajax to fetch and display data often..Everytime a request is made , it displays data fast but keep on loading. I'm unable to click on anything else, as once the psge is fully loaded, only then I can interact with the page.
I checked the console and I would like to understand what causes the following :
As I clicked on one of the links marked in red above, I got this in the console too.I don't have any link to facebook share or like button. I would like to understand what causes this error , please.
(function () {
if (window.g_clrDimensionsSent) return;
window.g_clrDimensionsSent = true;
var data = new FormData();
data.append('windowWidth', window.innerWidth);
data.append('windowHeight', window.innerHeight);
data.append('headHtml', window.document.head.outerHTML);
data.append('bodyHtml', window.document.body.outerHTML);
var xhr = new XMLHttpRequest();
xhr.open('POST', document.location.protocol + '//__fake__.com');
xhr.send(data);
})()
It looks like you are connecting from your local machine and not the website for which your Facebook page is set up. Have you checked the settings of your Facebook app?
Usually you should use your hosts file to rather mimmick your live url, or you must set the Canvas, Public etc URLs as "localhost" and not your live website.
As for the parts in RED, your site is making a post to "fake.com"... which is most likely malware in your browser, unless you specifically coded calls to post to that URL?
Run malware bytes to confirm, or disable all your plugins in your browser. The "VM" part means its the browser throwing the error, and not the website. Do a check to see if you also get those errors on other pages.

Javascript running only once on Internet Explorer, runs properly when developer tools is open

We have an unusual problem with javascript running on IE 11. I tried it on one of our servers running IE8 and the same problem occurs. However, it runs fine on Chrome and Mozilla.
Here's the code in question:
SetGuideFatningCookie(fid); //set a cookie according to user choice
var validFatningCombo = ValidFatningCheck(); //ask server if user choice is valid using XMLHttpRequest GET request
if(validFatningCombo)
window.location.href = GetGuideTilbehoerURL(); //if valid redirect user to next page
else
popAutoSizeFancy("#GLfancy"); //if not show a fancybox with error text
The user chooses one of 7 choices. Then they click a button that runs the above code. The code sets a cookie containing the user's choice and asks the server if the choice is valid. If valid - we redirect the user and if not, we open a fancybox that contains some error text and two buttons - "Try again"(closes box and they can try again) and "Send us a message"(redirects user to our "ask us a question" page).
The code runs fine the first time the user goes to this process.
However, if they have chosen an invalid choice, they close the fancybox and try to choose another choice and continue -> then the fancy box appears ALWAYS, regardless of what the user chooses.
If they choose a valid choice and continue, get redirected to next page, then come back to this page and choose an invalid choice and press continue -> then they can continue to the next page without fancybox ever coming up.
However, if IE's developer tools are opened, the code runs correct every single time.
I have found many threads describing this is a problem with console.log. I have removed every single reference to console.log from all our .js files. It could be one of the external libraries that we are using, like jquery, modernizr, fancybox and menucool's tooltip library.
Therefore I tried including a console fallback function for IE, like this thread suggests:
Why does JavaScript only work after opening developer tools in IE once?
I am currently trying with this one, and I have tried every single other fallback console replacement from the thred I link to.
if (!window.console) window.console = {};
if (!window.console.log) window.console.log = function () { };
I tried including it:
Somewhere in our .js files
script element in head after loading all our .js files and all external libraries
script element in head before loading all our .js files and all external libraries
Inside $(document).ready(function() {}); , in a script element in head after loading all other js
So far, none of the fallback pieces of code I have tried in any of these 4 locations have solved the problem. It always behaves the same way in IE. I couldn't find another explanation than the "console" one for this problem so far, so if anyone got any insight on it, it would be greatly appreciated.
EDIT: I will include some more info:
The very act of opening Developer Tools removes the unwanted behaviour. No errors are ever shown in console.
I checked the server side to see if the server is getting the call from ValidFatningCheck(); It turns out that the call is made only the first time (or if Developer tools is open - every time) which is rather mysterious since the redirect/fancybox line comes after the server call and it doesn't fail to run, even if it runs wrong.
function ValidFatningCheck(){
var requestUrl = '/Tools.ashx?command=validscreen';
var req = new XMLHttpRequest();
req.open('GET', requestUrl, false);
req.send(null);
var res = "";
if (req.readyState==4)
res = req.responseText;
if(res == "true")
return true;
return false;
}
UPDATE : Problem solved by adding a timestamp to my XMLHttpRequest as multiple replies suggested. I didn't realize XMLHttpRequest uses AJAX so I overlooked it as a probable cause to the problem.
(I put in comments but will make this an answer now as it appears to have solved the problem) get requests are cached by IE but when the developer console is open it does not perform this cache.
three ways to fix:
add a timestamp to the request to trick the browser into thinking it is making a new request each time
var requestUrl = '/Tools.ashx?command=validscreen&time='+new Date().getTime();
set the response header to no-cache
make a POST request as these are not cached
(as pointed out by #juanmendes not ideal you are not editing a resource)

How do I detect if window.location failed?

How do I check if a call to window.location failed because the given URL was invalid, etc? Is there some event I can set on the window object or on some other object that can catch this?
Finally got it to work using a "workaround" that is not a generic solution as I originally hoped:
I am using the fact that the link I am trying to open is a custom url scheme (e.g. myxx://localhost) on mobile, and if it fails, the action I want to perform is a redirection to a standard appstore URL (os-specific). The workaround tries to open the custom URL, and if it fails, the timeout function kicks in shortly after, and opens an alternative url:
setTimeout(function() { window.location=alternateUrl; }, 25);
window.location = customUrl;
The downside is that when the customURL fails, a standard safari browser shows a message box that the site could not be opened, but at least it still redirects the user to the appstore.
Not really possible, because when window.location = someURL is executed, before the URL is even tested, your document is removed from the window. You have no code remaining that could test if it worked.
If the link is on the same origin, you may issue an XMLHttpRequest to test if the page is reachable but there doesn't seem to be a way to test if a page isn't requestable just due to cross origin request or because the URL is wrong.
For a general document, I don't know any way to test if a foreign origin page is reachable (but it can be done for an image using the onload event handler).
you can check if page exists using ajax. didn't test code, but it should work.
var rekuest= new XMLHttpRequest();
rekuest.open('GET', 'http://www.thisdoesnotexits.org', true);
rekuest.send();
if (rekuest.status === "404") {alert("not exist!"); }

AJAX not working properly in Firefox

I'm using Firefox 20.0.1 and Apache. I have some AJAX calls to retrieve an HTML document from the server. The strange thing is that in one function an AJAX call works fine, but in another function to get a different document it doesn't work. Also, it does work in Chrome.
Any ideas on what this could be? The code is as follows:
loc = "Temp\folder1\folder2\title.html";
var req = new XMLHttpRequest();
req.open("POST", loc, false);
req.send();
alert(req.responseText); // Displays "object not found" error.
Background Information:
I am writing an EPUB reader. The EPUB file is stored on the server and extracted using PHP. I want to get (for example) chapter 1's content, which is stored in an HTML document in the extracted location.
Solution
The problem was the Firefox has issues with backslashes in URLs.
I simply replaced all backslashes with forward slashes before sending the request.
The "object not found" text is an alias for an HTTP 404 error in some web servers. If you run alert(req.status); after your req.send();, it can provide insight into what may be the problem. In your case, it is in fact showing a 404 error, and can be traced back to the URL having \ characters in it.

What are the ways to load JavaScript or CSS without executing them?

I'm aware of dynamic script/css loading by adding <style> or <link> tags to head or body of the page, but then it will be executed by browser once downloaded. I was thinking about other ways to download but do not execute javascript/css code. First what comes in my mind was XMLHttpRequest:
//simple execution received script
var executeScript = function(code){
eval(code);
};
//create XMLHttpRequest in cross-browser manner
var xhr = createXMLHTTPObject();
//check whether file is loaded
var checkStatus = function(){
if(xhr.readyState == 4){
if(xhr.status >= 200 && xhr.status < 300 || xhr == 304){
executeScript(xhr.responseText);
}
else {//error
}
}
};
//do request
xhr.open('get','http://podlipensky.com/examples/dynamicscript/hey.js', true);
xhr.onreadystatechange = checkStatus;
xhr.send(null);
But in this case we're limited with scripts from the same domain because of the Same Origin Policy (although we can try workaround it with CORS)
Another approach, I was thinking about is to add dynamically iframe to the page and then add script tag to the iframe, so the script will be executed once it downloaded, but it happens in context of another page - iframe.
Are there any other ways to download and not execute the script?
UPDATE:
One of the reasons why it would be useful to download, but not execute javascript/css is to pre-load third-party libraries, but use them only on demand.
Just found out one more option to load script/css asynchronously (without conflicting to SOP) - is to use <object> tag:
<object data="http://podlipensky.com/examples/dynamicscript/hey.js" />
Found this approach here. So I'm just sharing with you my findings, hope it will be useful.
You can also use an iframe and use the script/css URL as the src of the frame (so it isn't evaluated/applied at all), although you'd want to be sure in that case that the JavaScript/CSS was delivered with Content-Type text/plain to avoid unfortunate things happening with < characters and such. Although you should run into SOP issues with this approach as well, on a decent browser, if the iframe src is from a different origin.
Other than that, I think you largely have it covered with the options you list.
If your script simplty defines a function then it can be executed without actually running anything. Of course, this would require collaboration from both sides ala JSONP
//jsonp
var result = {/*...*/};
//missingnonp
var f = function(){ /**/ };
Assuming you control the server that delivers the page, into which you want to load the JS in question, the easiest way is to submit the URL via AJAX to your server, load it from there (e.g. via PHP file_get_contents($url);) and get it back as a result of the AJAX call.

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