I would like to be able to read information from a small page.
I have the address of a JSON service that displays the following information:
And I wish I could keep the number that appears.
I tested this example and work correctly, however when I try with my URL nothing happens. I do not know if I am to understand the problem correctly, but I wish someone could please help me.
If have any questions, I try to explain as best as possible.
I ask now apologize for the inconvenience.
The code that I used
var getJSON = function(url) {
return new Promise(function(resolve, reject) {
var xhr = new XMLHttpRequest();
xhr.open('get', url, true);
xhr.responseType = 'json';
xhr.onload = function() {
var status = xhr.status;
if (status == 200) {
resolve(xhr.response);
} else {
reject(status);
}
};
xhr.send();
});
};
getJSON('http://MYADDRESS/json.do?_ULN[1]').then(function(data) {
alert('Your Json result is: ' + data.result); //you can comment this, i used it to debug
result.innerText = data.result; //display the result in an HTML element
}, function(status) { //error detection....
alert('Something went wrong.');
});
You can't for security reasons. See the same origin policy for JavaScript.
There are some workarounds that exploit browser bugs or corner cases, but using them is not recommended.
The best approach is having a server-side proxy that receives Ajax requests, and in turn, sends HTTP requests to other servers. This should be carefully implemented by sanitizing input and whitelisting the types of requests that are sent, and the servers that are contacted.
Your problem exist because of the browser Same-origin policy.
One solution to your problem is to use the method JSON-P or CORS. The method is well explained here : http://json-p.org/ and here : http://www.sitepoint.com/jsonp-examples/.
Related
I'm doing the JavaScript challenges at FreeCodeCamp. One of them is to create a web page that retrieves and displays weather information.
First, I tried to use several providers (e. g. OpenWeatherMap, WeatherUnderground), which use the HTTP protocol to return weather data. It didn't work because of the mixed content error.
Next, I switched to a provider, which delivers the data via HTTPS. I got rid of the mixed content problem, but got another one:
XMLHttpRequest cannot load https://api.weatherbit.io/v1.0/current?lat=55.7767723&lon=37.6090795&units=S&key=XXXXXXXX. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'https://s.codepen.io' is therefore not allowed access. The response had HTTP status code 403.
I tried to implement CORS according to this tutorial:
function createCORSRequest(method, url) {
var xhr = new XMLHttpRequest();
if ("withCredentials" in xhr) {
// Check if the XMLHttpRequest object has a "withCredentials" property.
// "withCredentials" only exists on XMLHTTPRequest2 objects.
xhr.open(method, url, true);
} else if (typeof XDomainRequest != "undefined") {
// Otherwise, check if XDomainRequest.
// XDomainRequest only exists in IE, and is IE's way of making CORS requests.
xhr = new XDomainRequest();
xhr.open(method, url);
} else {
// Otherwise, CORS is not supported by the browser.
xhr = null;
}
return xhr;
}
[...]
var url = "https://api.weatherbit.io/v1.0/current?lat=" + position.coords.latitude + "&lon=" + position.coords.longitude + "&units=S&key=XXXXXXXX";
var xhr = createCORSRequest('GET', url);
if (xhr) {
xhr.onload = function() {
var responseText = xhr.responseText;
console.log("Response: " + responseText);
};
xhr.onerror = function() {
console.log('There was an error!');
};
xhr.send();
}
When I call xhr.send() I still get the error.
How can I fix it?
Note: I'm looking for a solution that will run in CodePen.
Update 1 (23.03.2017 11:35 MSK): I tried to implement sideshowbarker's answer and modified the code like this:
function getCurrent(json){
console.log("getCurrent called");
console.log(json.data.temp);
console.log(json.data.precip);
}
function updateWeather() {
if (navigator.geolocation) {
navigator.geolocation.getCurrentPosition(function(position) {
var url = "https://api.weatherbit.io/v1.0/current?callback=getCurrent&lat=" + position.coords.latitude + "&lon=" + position.coords.longitude + "&units=S&key=XXXXXXXXX";
console.log("url: " + url);
$.get(url, function(val){});
});
} else {
console.log("Cannot obtain location data");
};
}
updateWeather();
The result:
Update 2 (23.03.2017 13:29 MSK): This one works.
function getCurrent(json) {
console.log("getCurrent called");
console.log(JSON.stringify(json));
// TODO: Update the UI here
}
function updateWeather() {
if (navigator.geolocation) {
navigator.geolocation.getCurrentPosition(function(position) {
var url = "https://api.darksky.net/forecast/XXXXXXXXX/37.8267,-122.4233?callback=getCurrent";
var script = document.createElement('script');
script.src = url;
document.getElementsByTagName('head')[0].appendChild(script);
});
}
}
updateWeather();
The Weatherbit.io API doesn’t support cross-origin requests made from XHR.
Instead the API requires you make the requests using a script element with a JSONP callback:
<script>
function getCurrent(json){
console.log(json.data.temp)
console.log(json.data.precip)
}
</script>
<script
src="https://api.weatherbit.io/v1.0/current?callback=getCurrent&lat=NNN&lon=NNN&units=S&key=XX"></script>
Of course you likely want to have your code inject that script element with the URL and params.
That’s method of injecting the script element with a JSONP callback is the only direct method they support for using their API from a web app.
There’s no way your code will work if it instead makes the request to their API using XHR; they don’t send the necessary Access-Control-Allow-Origin response header, and so because that’s missing, your browser won’t let your client-side JavaScript access the response cross-origin.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS explains why.
The only way you could use XHR to work with their API is if you set up a CORS proxy using code from https://github.com/Rob--W/cors-anywhere/ or something similar—or if you send your request through an public CORS proxy like https://github.com/Rob--W/cors-anywhere/ (which you don’t want to do because that’d give the owner of that service access to your Weatherbit.io API key).
The way the proxy works is that instead of using weatherbit.io URL, you use a proxy URL like https://cors-anywhere.herokuapp.com/https://api.weatherbit.io/v1.0/current…, and the proxy sends it on to weatherbit.io, gets the response back, then adds the Access-Control-Allow-Origin response header to the response it hands back to your code and that the browser sees.
I was in the process of completing the Weather App in FCC and came across the same issue. I was able to get it to work with the following line:
$.getJSON("https://api.weatherbit.io/v1.0/current?lat=##&lon=##&key=##", function(data){};
For whatever reason, it wouldn't work with just "http://", I had to change it to "https://" in order for it to work.
Not sure if that helps anyone in the future.
I developed a small Javascript/jQuery program to access a collection of pdf files for internal use. And I wanted to have the information div of a pdf file highlighted if the file actually exist.
Is there a way to programmatically determine if a link to a file is broken? If so, How?
Any guide or suggestion is appropriated.
If the files are on the same domain, then you can use AJAX to test for their existence as Alex Sexton said; however, you should not use the GET method, just HEAD and then check the HTTP status for the expect value (200, or just less than 400).
Here's a simple method provided from a related question:
function urlExists(url, callback) {
var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function() {
if (xhr.readyState === 4) {
callback(xhr.status < 400);
}
};
xhr.open('HEAD', url);
xhr.send();
}
urlExists(someUrl, function(exists) {
console.log('"%s" exists?', someUrl, exists);
});
Issue is that JavaScript has the same origin policy so you can not grab content from another domain. This won't change by upvoting it (wondering about the 17 votes).
I think you need it for external links, so it is impossible just with .js ...
If the files are not on an external website, you could try making an ajax request for each file. If it comes back as a failure, then you know it doesn't exist, otherwise, if it completes and/or takes longer than a given threshold to return, you can guess that it exists. It's not always perfect, but generally 'filenotfound' requests are quick.
var threshold = 500,
successFunc = function(){ console.log('It exists!'); };
var myXHR = $.ajax({
url: $('#checkme').attr('href'),
type: 'text',
method: 'get',
error: function() {
console.log('file does not exist');
},
success: successFunc
});
setTimeout(function(){
myXHR.abort();
successFunc();
}, threshold);
You can $.ajax to it. If file does not exist you will get 404 error and then you can do whatever you need (UI-wise) in the error callback. It's up to you how to trigger the request (timer?) Of course if you also have ability to do some server-side coding you can do a single AJAX request - scan the directory and then return results as say JSON.
Like Sebastian says it is not possible due to the same origin policy. If the site can be published (temporarily) on a public domain you could use one of the link checker services out there. I am behind checkerr.org
As others have mentioned, because of JavaScript's same origin policy, simply using the function from the accepted answer does not work. A workaround to this is to use a proxy server. You don't have to use your own proxy for this, you can use this service for example: https://cors-escape.herokuapp.com (code here).
The code looks like this:
var proxyUrl = "https://cors-anywhere.herokuapp.com/";
function urlExists(url, callback) {
var sameOriginURL = proxyUrl + url;
var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function() {
if (xhr.readyState === 4) {
callback(xhr.status < 400);
}
};
xhr.open('HEAD', sameOriginURL);
xhr.send();
}
urlExists(someUrl, function(exists) {
console.log('"%s" exists?', someUrl, exists);
});
I'm getting these errors and I'm not sure what I'm doing wrong.
I'm new to making http requests using Javascript and I was wondering what I'm doing wrong in my request. If anyone can take a look and explain it to me, or point me to an already accepted answer, it would be greatly appreciated.
window.addEventListener("load", function(){
let url = "https://api.guildwars2.com";
let method = "GET";
let async = true;
let getData = "Get Data";
let request = new XMLHttpRequest();
request.onreadystatechange = function(){
let status = request.readyState;
let data = request.responseText;
if(status == 4 && status == 200){
console.log("Connection made");
}
}
request.open(method, url, async);
request.send();
console.log(request);
})
Since this question has a very detailed answer already elsewhere, I'm closing it.
This is because of CORS(Cross-Origin Resource Sharing), your are requesting different domain from your currently domain.
Read CORS Request for how to achieve this using CORS.
the last displayer error says that you are not allowed to retrieve data from another source ( CROSS ORIGIN REQUEST ) you'll have to configure your server to allow it.
I don't know what server you are using so here is a link to how to do it for many servers
I am using Kango framework to develop a cross-browser addon, using the following code I am making HEAD request's utilizing Kango.XHR which is getting successfully executed (as shown in HTTP DEBUGGER) and the code below in my background script also returns data.status == 200.
function doXHR(url) {
var details = {
method: 'HEAD',
url: url,
async: true
};
kango.xhr.send(details, function(data) {
if (data.status == 200) {
kango.console.log(data.status);
}
else { // something went wrong
kango.console.log('something went wrong');
}
});
};
Now, I want to get the value of Content-Length response header from the above but have no clue how to do that?
Ordinarily, you can read response headers with xhr.getReponseHeader. Depending on how Kango works, that method may already be available on your data object.
If data.getReponseHeader("Content-Length") doesn't work, then instead of using kngo.xhr.send, you might try imitating a normal Ajax call with kango.getXMLHttpRequest:
var request = kango.xhr.getXMLHttpRequest();
request.open('HEAD', url);
request.send(null);
request.onload = function() {
if(request.status == 200) {
console.log(request.getResponseHeader("Content-Length"));
console.log(request.responseText);
}
}
request.onerror = function() {
console.log("something went wrong");
}
Again, depending on how Kango operates under the hood, your server might need to serve an Access-Control-Expose-Headers response header to allow the client to read it. This won't likely be necessary, since extension code usually is not bound by the same origin policy, but I offer it only to help you iron out any possible inconsistencies in Kango's cross-platform API.
I am quite new in this area.
I need to find out how to make a request to my solr server using Ajax
How can I give a url(my solr server's url) in request
Any body know how to deal with this?
How can i make a request to the below mentioned url
http://mysite:8080/solr/select/?q=%2A%3A%2A&version=2.2&start=0&rows=100&indent=on
See here: Corrected the Code Snippet as below
function getProductIds() {
var xmlhttp;
if (window.XMLHttpRequest) xmlhttp = new XMLHttpRequest();
else xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) console.dir(xmlhttp);
else alert('no response');
var ajaxURL = "http://localhost:8080/solr/select/?q=*:*&version=2.2&start=0&rows=100&indent=on";
xmlhttp.open("GET", ajaxURL, true);
xmlhttp.send();
}
This is my code, it always showing "no response"
Thanks.
You will have to prepare the URL before sending in the request first get the URl using javascript and then encode it to ajax format like below
var URL = location.href;
var ajaxURL = encodeURIComponent(URL);
xmlhttp.open("GET",ajaxURL,true);
after reading your question clearly it seemed it is a static URL hence you can do below
var URL = "http://localhost:8080/blah blah blah";
xmlhttp.open("GET",URL,true);
Are you sure it is Get request. because get requests are most of the time cached. also log the response object into Firebug console and inspect the object to know more. Since you get no response that means the server did not send you anything for the request you made.
I'm just now working on XMLHttpRequests to solr as well and I was stuck with what seems like an identical problem. I too am quite new at this. However, the problem for me was that of same origin policy. Firefox seems to give very little feedback when this problem occurs. Chrome at least give you a error message (most of the time?).
In Chrome you can get around this, but only for development purposes, by starting it with the '--disable-web-security' command line option.
I'm yet to find a good workaround for this problem for Solr. In general you avoid the restriction by only using requests with relative paths, but that doesn't seem possible when doing a request to another port.
Ways to circumvent the policy (I haven't had time to study this too much yet)
$.ajax({
url: "url path",
context: document.body
}).done(function(data) {
alert(data);
});
This one also will work.