I'm very new to JavaScript and have been looking for a solution for a while with no success. I'm trying to use the Last.fm API to retrieve the currently playing track on my account. This is what I have so far:
<html>
<body>
<p>this is an experiment!</p>
<script type="text/javascript">
const request = new XMLHttpRequest();
request.open('GET', 'http://ws.audioscrobbler.com/2.0/?method=user.getrecenttracks&user='+[MY_USERNAME]+'&api_key='+[MY_API_KEY]+'&format=json');
request.send();
request.onload = () => {
if (request.status === 200) {
console.log("Success");
var song = JSON.parse(request.response).recenttracks.track[0].name;
console.log(song);
}
};
request.onerror = () => {
console.log("error")
};
</script>
</body>
</html>
and I get an error in the console when I open the file in my browser. Any help is appreciated :)
Update: everything worked when I gave it the direct URL, e.g. I took out the +s and put the API key directly in.
I checked your code with the test-account and it works fine. So probably you get the empty result, let's add some checks:
request.onload = () => {
if (request.status === 200) {
// look at the response
console.log(request.response);
const recenttracks = JSON.parse(request.response).recenttracks;
if (!recenttracks.track || !recenttracks.track.length) {
console.log('track is empty');
return;
}
const song = recenttracks.track[0].name;
console.log(song);
}
};
It looks like you should use onreadystatechange to catch the response instead of onload.
Example:
request.onreadystatechange = function() {
if (this.status == 200) {
console.log(this.responseText);
}
};
You can read more about XMLHttp Requests here:
https://www.w3schools.com/xml/ajax_xmlhttprequest_send.asp
I am loading my table on document.ready() from a json file as follows
document load....
$(document).ready(function () {
getSummaryData(function (data1) {
var dataarray=new Array();
dataarray.push(data1);
$('#summaryTable').DataTable({
data: dataarray,
"columns": [
---
---
and retrieving the data from a file as follows
function getSummaryData(cb_func1) {
$.ajax({
url: "data/summary.json",
success: cb_func1
});
console.log(cb_func1)
}
This was essentially loading dummy data so i could I could figure out how to load the table correctly etc. This works fine.
It does following
1. page loads
2. reads data from file
3. populates table
In reality, the data will not be loaded from file but will be returned from xhr response but I am unable to figure out
how to wire it all together. The use case is
POST a file via XMLHttpRequest
Get response
populate table (same data format as file)
I will post the file as follows...
<script>
var form = document.getElementById('form');
var fileSelect = document.getElementById('select');
var uploadButton = document.getElementById('upload');
---
form.onsubmit = function(event) {
event.preventDefault();
---
---
var xhr = new XMLHttpRequest();
// Open the connection.
xhr.open('POST', 'localhost/uploader', true);
// handler on response
xhr.onload = function () {
if (xhr.status === 200) {
console.log("resp: "+xhr);
console.log("resptxt: "+xhr.responseText);
//somehow load table with xhr.responseText
} else {
alert('ooops');
}
};
// Send the Data.
xhr.send(formData);
So ideally I need one empty row in the table or similar until someone uploads a file and then the table gets populated with the response.
Any help much appreciated.
var xhr1 = new XMLHttpRequest();
xhr1.open('POST', "youruploadserver.com/whatever", true);
xhr1.onreadystatechange = function() {
if (this.status == 200 && this.readyState == 4) {
console.log(this.responseText);
dostuff = this.responseText;
};//end onreadystate
xhr1.send();
It looks mostly correct, You want the this.readyState == 4 in there. what is your question, how to populate a table from the response?
That also depends on how you are going to send the data and how the server is going to parse the data, looks like you want to use a json format which is smart. JSON.stringify(formdata) before you send it and then make sure your server parses it as a json object Using body-parser depending on what server you are using. and then you JSON.stringify() the object to send it back.
Found on questions on is_ajax- Django request.is_ajax returning false - but that does not solve anything for me. I'm working around this by using 'ajax' in the GET...
I'm also trying to post through AJAX, but I can't find the results.
My AJAX handler is this:
function getContent(pageGet,method,post,target) {
if (typeof(post) ==='undefined') post = "";
if (typeof(method) ==='undefined') method = "GET";
if (typeof(target) ==='undefined') target = "body";
pageGet = '/?ajax=home/'+pageGet.replace('?','&');
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
var body = document.getElementById(target);
if (this.readyState == 4) {
if (this.status == 200) {
body.innerHTML = this.responseText;
var scripts = body.getElementsByTagName("script");
var script_amount = scripts.length;
for( var i = 0; i < script_amount; ++i)
eval(scripts[i].innerHTML);
} else if (this.status == 0) {
getContent('main.html');
} else {
body.innerHTML = "Failed with "+this.status;
}
}
};
xhttp.open(method, pageGet, true);
xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xhttp.send(post);
return false;
}
As, I said this never registers in is_ajax, but AJAX is working fine. This is the value of pageGet:
/?ajax=home/forms/genericForm.html&form=UserForm
and this the value of post:
username=sdf&password=dfs&=Submit&
Obviously method="POST".
This gets to my view.py, and the request.GET is populated properly with 'ajax' (my workaround for the other problem), and 'form'. But request.POST is empty, as well as request.body which is alluded to here - Ajax POST not sending data when calling 'request.POST' in Django view and some other answer.
There are also mentions of a "CSRF" token, but I don't know what I'm doing wrong. The view code just prints request.GET,body, and POST, and is_ajax.
Please, only pure JS solutions.
Progress
I managed to get post to work - by default CSRF is enabled, and you must set the AJAX header with it. If anyone figures the is_ajax part I'd be obliged.
I have an HTML page with a button on it. When I click on that button, I need to call a REST Web Service API. I tried searching online everywhere. No clue whatsoever. Can someone give me a lead/Headstart on this? Very much appreciated.
I'm surprised nobody has mentioned the new Fetch API, supported by all browsers except IE11 at the time of writing. It simplifies the XMLHttpRequest syntax you see in many of the other examples.
The API includes a lot more, but start with the fetch() method. It takes two arguments:
A URL or an object representing the request.
Optional init object containing the method, headers, body etc.
Simple GET:
const userAction = async () => {
const response = await fetch('http://example.com/movies.json');
const myJson = await response.json(); //extract JSON from the http response
// do something with myJson
}
Recreating the previous top answer, a POST:
const userAction = async () => {
const response = await fetch('http://example.com/movies.json', {
method: 'POST',
body: myBody, // string or object
headers: {
'Content-Type': 'application/json'
}
});
const myJson = await response.json(); //extract JSON from the http response
// do something with myJson
}
Your Javascript:
function UserAction() {
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
alert(this.responseText);
}
};
xhttp.open("POST", "Your Rest URL Here", true);
xhttp.setRequestHeader("Content-type", "application/json");
xhttp.send("Your JSON Data Here");
}
Your Button action::
<button type="submit" onclick="UserAction()">Search</button>
For more info go through the following link (Updated 2017/01/11)
Here is another Javascript REST API Call with authentication using json:
<script type="text/javascript" language="javascript">
function send()
{
var urlvariable;
urlvariable = "text";
var ItemJSON;
ItemJSON = '[ { "Id": 1, "ProductID": "1", "Quantity": 1, }, { "Id": 1, "ProductID": "2", "Quantity": 2, }]';
URL = "https://testrestapi.com/additems?var=" + urlvariable; //Your URL
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = callbackFunction(xmlhttp);
xmlhttp.open("POST", URL, false);
xmlhttp.setRequestHeader("Content-Type", "application/json");
xmlhttp.setRequestHeader('Authorization', 'Basic ' + window.btoa('apiusername:apiuserpassword')); //in prod, you should encrypt user name and password and provide encrypted keys here instead
xmlhttp.onreadystatechange = callbackFunction(xmlhttp);
xmlhttp.send(ItemJSON);
alert(xmlhttp.responseText);
document.getElementById("div").innerHTML = xmlhttp.statusText + ":" + xmlhttp.status + "<BR><textarea rows='100' cols='100'>" + xmlhttp.responseText + "</textarea>";
}
function callbackFunction(xmlhttp)
{
//alert(xmlhttp.responseXML);
}
</script>
<html>
<body id='bod'><button type="submit" onclick="javascript:send()">call</button>
<div id='div'>
</div></body>
</html>
$("button").on("click",function(){
//console.log("hii");
$.ajax({
headers:{
"key":"your key",
"Accept":"application/json",//depends on your api
"Content-type":"application/x-www-form-urlencoded"//depends on your api
}, url:"url you need",
success:function(response){
var r=JSON.parse(response);
$("#main").html(r.base);
}
});
});
I think add if (this.readyState == 4 && this.status == 200) to wait is better:
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
// Typical action to be performed when the document is ready:
var response = xhttp.responseText;
console.log("ok"+response);
}
};
xhttp.open("GET", "your url", true);
xhttp.send();
If that helps anyone, if you are ok with an external library then I can vouch for Axios, which has a pretty clean API and rich documentation to deal with REST calls, here's an example below:-
const axios = require('axios');
axios.get('/user?ID=12345')
.then(function (response) {
// handle success
console.log(response);
});
Before we try to put anything on the front end of the website, let's open a connection the API. We'll do so using XMLHttpRequest objects, which is a way to open files and make an HTTP request.
We'll create a request variable and assign a new XMLHttpRequest object to it. Then we'll open a new connection with the open() method - in the arguments we'll specify the type of request as GET as well as the URL of the API endpoint. The request completes and we can access the data inside the onload function. When we're done, we'll send the request.
// Create a request variable and assign a new XMLHttpRequest object to it.
var request = new XMLHttpRequest()
// Open a new connection, using the GET request on the URL endpoint
request.open('GET', 'https://ghibliapi.herokuapp.com/films', true)
request.onload = function () {
// Begin accessing JSON data here
}
}
// Send request
request.send()
By far, the easiest for me is Axios. You can download the node module or use the CDN for your simpler projects.
CDN:
<script src="https://cdn.jsdelivr.net/npm/axios/dist/axios.min.js"></script>
Code example for GET/POST:
let postData ={key: "some value"}
axios.get(url).then(response =>{
//Do stuff with the response.
})
axios.post(url, postData).then(response=>{
//Do stuff with the response.
});
Without a doubt, the simplest method uses an invisible FORM element in HTML specifying the desired REST method. Then the arguments can be inserted into input type=hidden value fields using JavaScript and the form can be submitted from the button click event listener or onclick event using one line of JavaScript. Here is an example that assumes the REST API is in file REST.php:
<body>
<h2>REST-test</h2>
<input type=button onclick="document.getElementById('a').submit();"
value="Do It">
<form id=a action="REST.php" method=post>
<input type=hidden name="arg" value="val">
</form>
</body>
Note that this example will replace the page with the output from page REST.php.
I'm not sure how to modify this if you wish the API to be called with no visible effect on the current page. But it's certainly simple.
Usual way is to go with PHP and ajax. But for your requirement, below will work fine.
<body>
https://www.google.com/controller/Add/2/2<br>
https://www.google.com/controller/Sub/5/2<br>
https://www.google.com/controller/Multi/3/2<br><br>
<input type="text" id="url" placeholder="RESTful URL" />
<input type="button" id="sub" value="Answer" />
<p>
<div id="display"></div>
</body>
<script type="text/javascript">
document.getElementById('sub').onclick = function(){
var url = document.getElementById('url').value;
var controller = null;
var method = null;
var parm = [];
//validating URLs
function URLValidation(url){
if (url.indexOf("http://") == 0 || url.indexOf("https://") == 0) {
var x = url.split('/');
controller = x[3];
method = x[4];
parm[0] = x[5];
parm[1] = x[6];
}
}
//Calculations
function Add(a,b){
return Number(a)+ Number(b);
}
function Sub(a,b){
return Number(a)/Number(b);
}
function Multi(a,b){
return Number(a)*Number(b);
}
//JSON Response
function ResponseRequest(status,res){
var res = {status: status, response: res};
document.getElementById('display').innerHTML = JSON.stringify(res);
}
//Process
function ProcessRequest(){
if(method=="Add"){
ResponseRequest("200",Add(parm[0],parm[1]));
}else if(method=="Sub"){
ResponseRequest("200",Sub(parm[0],parm[1]));
}else if(method=="Multi"){
ResponseRequest("200",Multi(parm[0],parm[1]));
}else {
ResponseRequest("404","Not Found");
}
}
URLValidation(url);
ProcessRequest();
};
</script>
I'm using some JavaScript to send an Ajax request to an Arduino webserver and change the HTML on a webpage.
In Safari this has been working great, but when I try to load it in Firefox and Google Chrome the document elements never update. In the debugger consoles I can see the requests and responses coming back so I'm guessing that there is an issue with parsing the response to an array?
Here is the code:
function GetSwitchState()
{
nocache = "&nocache=" + Math.random() * 1000000;
var request = new XMLHttpRequest();
request.onreadystatechange = function()
{
if (this.readyState == 4) {
if (this.status == 200) {
if (this.responseText != null) {
var response = this.responseText;
var comma = ",";
var inputArray = response.split(comma);
var green = inputArray[0];
var red = inputArray[1];
var fault = inputArray[2];
var counter = inputArray[3];
document.getElementById('green').innerHTML = green;
document.getElementById("red").innerHTML = red;
document.getElementById("status").innerHTML = fault;
document.getElementById("cars").innerHTML = counter;
}
}
}
}
request.open("GET", "url" + nocache, true);
request.send(null);
setTimeout('GetSwitchState()', 1000);
}
The response from the Arduino webserver is four comma-separated values.
Okay it looks like the issue was actually getting past the
{
if (this.readyState == 4) {
if (this.status == 200) {
arguments. When I changed it to:
{
if(response.readState == 4) {
I was able to move past that statement in firefox. To get the status to 200 instead of 0 I needed to modify the response header on the arduino side to include:
Access-Control-Allow-Origin: *
To allow Cross Origin Domain Requests in FireFox. Once I made these changes the code works great, I guess I was barking up the wrong tree with my array assumption.
Thanks for the help!
What I did today was pretty much the same!
When I ran an Ajax request to a PHP file and wanted to return an array I needed to specify the return-datatype as "json". In my PHP file I then returned my values like this:
return json_encode(array(
'success' => false,
'error' => $_POST['password_hashed']
));
I was acctually using jQuery to run the request. That looks like this:
$.ajax({
type: 'POST',
url: 'script.php',
data: 'password_hashed=' + hex_sha512(str_password) + '&email=' + str_email, //Clientside password hashing
cache: false,
dataType: 'json',
success: function(value){
//Ajax successfully ran
alert(value.success + '_' + value.error); //=false_[hash]
},
error: function(){
//Ajax error occured -> Display error message in specified element
alert('error with request');
}
});
I just started with Ajax two days ago, and this may not help a lot, but it is worth trying.