No output error when attempting to display json - javascript

When the following code executes it's showing no output. Can anyone tell me where I am going wrong?
html file:
<head>
<script type = "text/javascript">function ajax_get_json()
{
var hr = new XMLHTTPRequest();
hr.open("GET","mylist.json",true);
hr.setRequestHeader("Content-type :application/json",true);
hr.onread
ystatechange = function()
{
if(hr.readyState == 4 && hr.status == 200)
{
var data = JSON.parse(hr.responseText);
var results=document.getElementById("results");
results.innerHTML = data.user;
}
}
hr.send(null);
results.innerHTML = "requesting...";
}
</script>
</head>
<body>
<div id="results"></div>
<script type = "text/javascript">ajax_get_json();</script>
</body>
json file:
{ "user":"John", "age":22, "country":"US" }

XMLHTTPRequest() must be XMLHttpRequest(). The JavaScript file looks like:
function request() {}
request();
HTML
<script src="file.js"></script>
With var data = JSON.parse(hr.responseText); you have on object.
Go through the object:
for(var key in obj) {}
and store key and obj[key] in innerHTML to see a result.
Complete JavaScript file:
function request() {
var hr = new XMLHttpRequest();
hr.onreadystatechange = function() {
if (hr.readyState == 4 && hr.status == 200) {
var data = JSON.parse(hr.responseText); // object
var results = document.getElementById("results");
results.innerHTML = "";
for(var key in data) {
results.innerHTML += key + " " + data[key] + "<br>";
}
}
}
hr.open("GET", "mylist.json", true);
hr.send();
results.innerHTML = "requesting...";
}
request();
(Please change the title of your question. Be specific!
How to ask)

Related

Function output empty by succesfull AJAX response

There's an issue with my function in the AJAX.
I create an AJAX call to a PHP file that returns JSON.
For loop this JSON I created a fucntion that I run if the AJAX is successfull.
But in practice the data is empty.
<script>
document.getElementById("getproducts").addEventListener("submit", sendAjax);
function sendAjax(event) {
var q = document.getElementById('search').value;
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
display(this.responseText);
}
}
xhttp.open("POST", "results.php", true);
xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xhttp.send('search='+q);
event.preventDefault();
}
function display( jsdata ){
for ( var key in jsdata ){
var htmltabel = '';
var datanode = document.createElement("div");
htmltabel += '<div class="id">' + jsdata[key]['id'] + '</div>';
content = htmltabel;
datanode.innerHTML = content;
document.getElementById("resultt").appendChild(datanode);
}
}
</script>
If I code the JSON hardcode in the function like this than everything is okay.
var hardcoded = {"1736":{"id":"1736","post_title":"Test explode","_sku":"12345","_stock":null,"_price":"9.50"}}
//PART OF THE CODE
if (this.readyState == 4 && this.status == 200) {
display(hardcoded);
}
How can I fix this that the function use the responded JSON?
here is a corrected script, You should just convert the responseData from string to Json Object!
document.getElementById("getproducts").addEventListener("submit", sendAjax);
function sendAjax(event) {
var q = document.getElementById('search').value;
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
display( JSON.parse(this.responseText) ); // You should convert the response from string to a valid JSON
}
}
xhttp.open("POST", "results.php", true);
xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xhttp.send('search='+q);
event.preventDefault();
}
function display( jsdata ){
for ( var key in jsdata ){
var htmltabel = '';
var datanode = document.createElement("div");
htmltabel += '<div class="id">' + jsdata[key]['id'] + '</div>';
content = htmltabel;
datanode.innerHTML = content;
document.getElementById("resultt").appendChild(datanode);
}
}

Json parser and loop scheme

How can I loop my json file using my script, eg: I should choose whether to loop Schema A or Schema B.
My json file is:
{
"A":[
{
"id":"1",
"title":"Primo"
},
{
"id":"2",
"title":"Secondo"
}
],
"B":[
{
"id":"1",
"title":"Primo"
},
{
"id":"2",
"title":"Secondo"
}
]
}
Maybe setting a variable so as to define the scheme I have to display
My javascript file is:
var xmlhttp = new XMLHttpRequest();
var url = "myTutorials.txt";
xmlhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
var myArr = JSON.parse(this.responseText);
myFunction(myArr);
}
};
xmlhttp.open("GET", url, true);
xmlhttp.send();
function myFunction(arr) {
var out = "";
var i;
for(i = 0; i < arr.length; i++) {
out += arr[i].id + ' - ' + arr[i].title + '<br>';
}
document.getElementById("id01").innerHTML = out;
}
var xmlhttp = new XMLHttpRequest();
var url = "myTutorials.txt";
xmlhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
var obj= JSON.parse(this.responseText);
myFunction(obj, 'A');
}
};
xmlhttp.open("GET", url, true);
xmlhttp.send();
function myFunction(obj, key) {
var arr = obj[key];
var out = "";
var i;
for(i = 0; i < arr.length; i++) {
out += arr[i].id + ' - ' + arr[i].title + '<br>';
}
document.getElementById("id01").innerHTML = out;
}
Assuming that what you presented as JSON file is a response form network and is passed to myFunction, then why not to do something like:
let myRootArray;
if(/* some confitions */) {
myRootArray = myArr.A
} else {
myRootArray = myArr.B
}
myFunction(myRootArray );
Beside that, your names are a bit confusing, var myArr = JSON.parse(this.responseText);, while JSON.parse will return object, not an array.

How to add Node.js result in my HTML project?

this is my project: http://cryptotipsitalia.sytes.net/.
I want add Ethereum value down to "Valore BTC" with Node.js: https://www.npmjs.com/package/crypto-price.
How can I add it?
That's my code:
function getValueBTC() { <!-- chiamata API --> /
var xmlhttp = new XMLHttpRequest();
var url = "https://api.coindesk.com/v1/bpi/currentprice.json";
var output;
console.log(url);
xmlhttp.onreadystatechange = function () {
if (this.readyState == 4 && this.status == 200) {
output = this.responseText;
var obj = JSON.parse(output);
var rightValue = (obj.bpi.EUR.rate).substring(0,obj.bpi.EUR.rate.length-2); /* eliminazione ultime due cifre */
document.getElementById("cellaValoreBTC").innerHTML= obj.bpi.EUR.symbol + " " + rightValue;
}
};
xmlhttp.open("GET", url, true);
xmlhttp.setRequestHeader("Content-type", "text/plain");
xmlhttp.send();
}
let price = require('crypto-price');
price.getCryptoPrice('EUR', 'ETH').then(obj => {
console.log(obj.price); // It will print ETH rate per BTC
document.getElementById("cellaValoreETH").innerHTML = obj.price;
}).catch(err => {
console.log(err);
});
table><tr><td width="75%">VALORE BTC:</td></tr><tr id="cellaValoreBTC" width="75%"></tr><tr><td width="75%">VALORE ETH:</td></tr><tr id="cellaValoreETH" width="75%"></table>
Why "document.getElementById("cellaValoreBTC").innerHTML = obj.price;" doesnt' work?
How can I add obj.price in my HTML code?
Thanks

How to get multiple XMLHttpRequests to occur serially?

I have the following code, which works (sort of). When I run it, the page displays information about the two coins, but returns 'undefined' for the coin price. The call to alert() indicates that the getCoinPrice function is running AFTER the main code. How do you execute the code so that the function call happens serially? If that's not possible, would it be better to learn to use the Fetch API?
Here's the code, in its entirety:
<html>
<body>
<h2>Use the XMLHttpRequest to get the content of a file.</h2>
<p id="demo"></p>
<script>
function getCoinPrice(id) {
var xhr = new XMLHttpRequest();
var URL = "https://api.coinmarketcap.com/v2/ticker/" + id + "/";
xhr.onreadystatechange = function() {
if (xhr.readyState == 4 && xhr.status == 200) {
var Obj = JSON.parse(xhr.responseText);
var price = Obj.data.quotes.USD.price;
alert(price);
return(price);
}
}
xhr.open("GET", URL, true);
xhr.send();
}
var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
var myObj = JSON.parse(this.responseText);
var coins = [ "BTC","ETH" ]
for(j=0; j < coins.length; j++) {
for(i=0; i < myObj.data.length; i++) {
if (myObj.data[i].symbol == coins[j]) {
document.getElementById("demo").innerHTML +=
myObj.data[i].id + "," + myObj.data[i].name + "," +
myObj.data[i].symbol + "," +
getCoinPrice( myObj.data[i].id ) + "<br>" ;
}
}
}
}
};
xmlhttp.open("GET", "https://api.coinmarketcap.com/v2/listings/", true);
xmlhttp.send();
</script>
</body>
</html>

Calling data from JSON file using AJAX

I am trying to load some data from my JSON file using AJAX. The file is called external-file.json. Here is the code, it includes other parts that haven't got to do with the data loading.The part I'm not sure of begins in the getViaAjax funtion. I can't seem to find my error.
function flip(){
if(vlib_front.style.transform){
el.children[1].style.transform = "";
el.children[0].style.transform = "";
} else {
el.children[1].style.transform = "perspective(600px) rotateY(-180deg)";
el.children[0].style.transform = "perspective(600px) rotateY(0deg)";
}
}
var vlib_front = document.getElementById('front');
var el = document.getElementById('flip3D');
el.addEventListener('click', flip);
var word = null; var explanation = null;
var i=0;
function updateDiv(id, content) {
document.getElementById(id).innerHTML = content;
document.getElementById(id).innerHTML = content;
}
updateDiv('the-h',word[i]);
updateDiv('the-p',explanation[i])
function counter (index, step){
if (word[index+step] !== undefined) {
index+=step;
i=index;
updateDiv('the-h',word[index]);
updateDiv('the-p',explanation[index]);
}
}
var decos = document.getElementById('deco');
decos.addEventListener('click', function() {
counter(i,-1);
}, false);
var incos = document.getElementById('inco');
incos.addEventListener('click', function() {
counter(i,+1);
}, false);
function getViaAjax("external-file.json", callback) { // url being the url to external File holding the json
var r = new XMLHttpRequest();
r.open("GET", "external-file.json", true);
r.onload = function() {
if(this.status < 400 && this.status > 199) {
if(typeof callback === "function")
callback(JSON.parse(this.response));
} else {
console.log("err");// server reached but gave shitty status code}
};
}
r.onerror = function(err) {console.log("error Ajax.get "+url);console.log(err);}
r.send();
}
function yourLoadingFunction(jsonData) {
word = jsonData.words;
explanation = jsonData.explanation;
updateDiv('the-h',word[i]);
updateDiv('the-p',explanation[i])
// then call whatever it is to trigger the update within the page
}
getViaAjax("external-file.json", yourLoadingFunction)
As #light said, this:
function getViaAjax("external-file.json", callback) { // url being the url to external File holding the json
var r = new XMLHttpRequest();
r.open("GET", "external-file.json", true);
Should be:
function getViaAjax(url, callback) { // url being the url to external File holding the json
var r = new XMLHttpRequest();
r.open("GET", url, true);
I built up a quick sample that I can share that might help you isolate your issue. Stand this up in a local http-server of your choice and you should see JSON.parse(xhr.response) return a javascript array containing two objects.
There are two files
data.json
index.html
data.json
[{
"id":1,
"value":"foo"
},
{
"id":2,
"value":"bar"
}]
index.html
<html>
<head>
</head>
<body onload="so.getJsonStuffs()">
<h1>so.json-with-ajax</h1>
<script type="application/javascript">
var so = (function(){
function loadData(data){
var list = document.createElement("ul");
list.id = "data-list";
data.forEach(function(element){
var item = document.createElement("li");
var content = document.createTextNode(JSON.stringify(element));
item.appendChild(content);
list.appendChild(item);
});
document.body.appendChild(list);
}
var load = function()
{
console.log("Initializing xhr");
var xhr = new XMLHttpRequest();
xhr.onload = function(e){
console.log("response has returned");
if(xhr.status > 200
&& xhr.status < 400) {
var payload = JSON.parse(xhr.response);
console.log(payload);
loadData(payload);
}
}
var uri = "data.json";
console.log("opening resource request");
xhr.open("GET", uri, true);
xhr.send();
}
return {
getJsonStuffs : load
}
})();
</script>
</body>
</html>
Running will log two Javascript objects to the Dev Tools console as well as add a ul to the DOM containing a list item for every object inside the data.json array

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