Ajax Yelp API Call from Javascript - javascript

I'm trying to make a call to the Yelp API from JavaScript, but getting an error. Below is my code. I believe I will have to use Oauth, but I don't know where should I put it in the header.
function doAjax(){
var xhr = new XMLHttpRequest();
var url = "http://api.yelp.com/v2/searchterm=cream+puffs&location=chicago";
xhr.onreadystatechange = function(){
if(xhr.readyState == 4 && xhr.status == 200){
var some = JSON.parse(xhr.responseText);
}
}
xhr.open('GET', url, true);
xhr.send();
}

The problem is that you are trying to access a resource that is on a different domain from your application. In this case your application resides on http://fiddle.jshell.net and the resource is at http://api.yelp.com.
CORS is one way to get around this, see here:
http://en.wikipedia.org/wiki/Cross-origin_resource_sharing

Related

How to everytime reload web, and get the newest data from back-end

What my purpose is below
Visting a web and the js.file in this web will load php file, and it will return data to html.
It's meaning every time when I reload web, I will get newest data.
I have try this in js.file
let XML = new XMLHttpRequest();
XML.open('post', url, true);
XML.send('mydata');
then use responseText to get data I want
Indeed, I don't need send any data.
I can do what I want to do, but I am not sure this way is right or not.
Because I think ajax should not use in this case, it must be send something and return something.
What you are saying is you only want to get data without sending anything which is called a http get request, you can do that as below.
function get(url)
{
var xm = new XMLHttpRequest();
// false for synchronous
xm.open("GET",url,false);
xm.send(null);
return xm.responseText;
}
console.log(get('your Url'));
You need to specify the url of your Http Endpoint ( Back-End ).
If your are making a asynchronous request then below code works,,
function get(theUrl, callback)
{
var xmlHttp = new XMLHttpRequest();
xmlHttp.onreadystatechange = function() {
if (xmlHttp.readyState == 4 && xmlHttp.status == 200)
callback(xmlHttp.responseText);
}
// true for asynchronous
xmlHttp.open("GET", theUrl, true);
xmlHttp.send(null);
}
get('your url',(responseText)=>{
console.log(responsetext);
});

Fetch XML without getting blocked (CORB)

For example I want to fetch https://www.w3schools.com/xml/simple.xml
to my website http://example.com.
This is the code
var xhr = new XMLHttpRequest();
xhr.open("GET", 'https://www.w3schools.com/xml/simple.xml', true);
xhr.onload = function () {
if (xhr.readyState === 4 && this.status === 200) {
console.log(this);
}
}
xhr.send();
I'm getting an empty response and a warning saying
Cross-Origin Read Blocking (CORB) blocked cross-origin response https://www.w3schools.com/xml/simple.xml with MIME type text/xml. See https://www.chromestatus.com/feature/5629709824032768 for more details.
Then I had been studying these CORB rules. Some developers are saying that it is not possible to get data from another origin.
But is it really the case?
In the project I'm working on, it is a public xml feed, and since the owner are updating the feed quite often - and I would like to have my website in sync with the feed - I assume it is not possible? Do I really have to create a xml file, and copy-paste the xml data and upload it to my server each time?
Or is there a way to fetch this data directly from the url somehow?
You could create a PHP script like this:
<?php
header("Content-type: text/xml");
echo file_get_contents('https://www.w3schools.com/xml/simple.xml');
?>
Call this simple.php and then amend your Javascript to call simple.php instead:
var xhr = new XMLHttpRequest();
xhr.open("GET", 'simple.php', true);
xhr.onload = function () {
if (xhr.readyState === 4 && this.status === 200) {
console.log(this);
}
}
xhr.send();

Exchange API using javascript

I'm using javascript to use the API on this site https://www.luno.com/en/api and I don't understand why I am not receiving any data. When if I just enter this url: https://api.mybitx.com/api/1/ticker?pair=XBTZAR I do receive data in the broswer.
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
var myObj = JSON.parse(this.responseText);
document.getElementById("luno").innerHTML = myObj.bid;
}
};
xmlhttp.open("GET", "https://api.mybitx.com/api/1/ticker?pair=XBTZAR", true);
xmlhttp.send();
Why is it not returning anything?
You have a trouble with CORS requests.
You can see similar error on your developer console:
You can't call API from JS code because api.mybitx.com blocks cross domain request.
You have a several solutions:
Create own server side API method.
Call this method from your JS code.
Inside the API method call api.mybitx.com API using WebRequest or RestSharp.
If you want to do it only on JS code, then you need to use EasyXDM library.
For me the first solution is more simpler and more correct.

Using javascript to submit a post request to a server

I am working on a web crawler that can integrate with our partner portals and submit post requests to make bid changes.
The trouble is that the crawler runs in an environment which cannot execute jQuery, only native Javascript.
I have determined that the following AJAX code successfully sends the post request:
$.ajax({
type: "POST",
url: "http://acp.example.com/campaigns/122828",
data: "data-string"
});
Is there a way to translate the above statement into native javascript so that the crawler can execute it?
UPDATE
When executing hex494D49's native Javascript below, I am receiving a "NetworkError: 404 Not Found - http://acp.fyber.com/campaigns/122828" message.
However, when I execute the original AJAX code in firebug, it successfully sends the POST request.
Any idea why the same url would return a 404 error using native Javascript as opposed to AJAX?
Thanks
Sending AJAX request using POST method
var xhr = new XMLHttpRequest();
var url = "url";
var data = "email=hey#mail.com&password=101010";
xhr.open("POST", url, true);
xhr.setRequestHeader("Content-type","application/x-www-form-urlencoded");
xhr.onreadystatechange = function () {
if (xhr.readyState == 4 && xhr.status == 200) {
// do something with response
console.log(xhr.responseText);
}
};
xhr.send(data);
Sending AJAX request using GET method
xhr = new XMLHttpRequest();
var url = "url?email=hey#mail.com&password=101010";
xhr.open("GET", url, true);
xhr.onreadystatechange = function () {
if (xhr.readyState == 4 && xhr.status == 200) {
// do something with response
console.log(xhr.responseText);
}
}
xhr.send();
To avoid unexpected requests to the server, it's a good practice to use encodeURIComponent() method on any user-entered parameters that will be passed as part of a URI.

Ajax - "Access-Control-Allow-Origin" Error

I'm trying to work with the Livestream API to see if a certain channel is live but keep getting this error:
XMLHttpRequest cannot load http://channel.api.livestream.com/1.0/livestatus?channel=huskystarcraft. Origin http://www.webdevstl.com is not allowed by Access-Control-Allow-Origin.
Do I need to run it through PHP or am I doing something wrong in my ajax call? It's pretty straight forward code:
function getActive(){
if(window.XMLHttpRequest)
{
xmlhttp = new XMLHttpRequest();
}
else
{
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange = function()
{
if(xmlhttp.readyState == 4 && xmlhttp.status == 200)
{
var json = JSON.parse(xmlhttp.responseText);
console.log(json);
}
}
xmlhttp.open("GET", "http://channel.api.livestream.com/1.0/livestatus?channel=huskystarcraft", true);
xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlhttp.send();
}
getActive();
You're running into restrictions imposed by the Same Origin Policy. In short, AJAX calls to a different domain are prohibited and will fail - unless explicitly permitted by the remote host.
You need to either use JSONP (mostly applicable to data returned by APIs) or proxy the request through your own server/domain.
CORS would also be an option, but that assumes you having access to the remote server's config.

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