# Error on loadXML(URL) within P5js

**URL:** <https://discourse.processing.org/t/error-on-loadxml-url-within-p5js/25709>\
**Category:** Beginners\
**Created:** [November 25, 2020, 6:18pm UTC](https://discourse.processing.org/t/error-on-loadxml-url-within-p5js/25709 "2020-11-25T18:18:32Z")\
**Posts on this page:** 8\
**Page:** 1

<div class="post-metadata">

**Author:** ![CAVUCO](https://avatars.discourse-cdn.com/v4/letter/c/a9a28c/32.png) [@CAVUCO](https://discourse.processing.org/u/CAVUCO)\
**Post date:** [November 25, 2020, 6:18pm UTC](https://discourse.processing.org/t/error-on-loadxml-url-within-p5js/25709/1 "2020-11-25T18:18:32Z")

</div>

```auto
var url ='https://www.aviationweather.gov/adds/dataserver_current/httpparam?dataSource=metars&requestType=retrieve&format=xml&minLat=25&minLon=-125&maxLat=50&maxLon=-66&hoursBeforeNow=1&stationstring=K*&fields=station_id,latitude,longitude,flight_category';

var airportData;

var xml;

function preload() {
 xml = loadXML(url, gotData); //if I comment out this line it runs without error
  
}

function setup() {
  createCanvas(1280,564); //equidistant
  
  }

function gotData(xml){
  airportData=xml.getChildren('METAR');
}

```

Get the following error,

Uncaught TypeError: Cannot read property ‘split’ of undefined (: line 56)

loadXML is part of the core library of P5.js is it not?

---

<div class="post-metadata">

**Author:** ![GoToLoop](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/gotoloop/32/86_2.png) [@GoToLoop](https://discourse.processing.org/u/GoToLoop)\
**Post date:** [November 25, 2020, 6:37pm UTC](https://discourse.processing.org/t/error-on-loadxml-url-within-p5js/25709/2 "2020-11-25T18:37:06Z")

</div>

> **[loadXML() from EkstraBladet via Proxy](https://Bl.ocks.org/GoSubRoutine/5bdec67b4f70080bfddb6c0607cb6c70)**
>
> GoSubRoutine’s Block 5bdec67b4f70080bfddb6c0607cb6c70

  
https://codepen.io/GoSubRoutine/embed/preview/Qdjmrm?height=300&slug-hash=Qdjmrm&default-tabs=js,result&host=https://codepen.io

---

<div class="post-metadata">

**Author:** ![noel](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/noel/32/213_2.png) [@noel](https://discourse.processing.org/u/noel)\
**Post date:** [November 25, 2020, 6:37pm UTC](https://discourse.processing.org/t/error-on-loadxml-url-within-p5js/25709/3 "2020-11-25T18:37:07Z")

</div>

> [@CAVUCO](#):
>
> loadXML is part of the core library of P5.js is it not?

Yes but read thi[s link.](https://discourse.processing.org/t/issue-loading-xml-feed-in-p5js/8212)  
Edit : Hehe, Answered at the same time as post above.

---

<div class="post-metadata">

**Author:** ![CAVUCO](https://avatars.discourse-cdn.com/v4/letter/c/a9a28c/32.png) [@CAVUCO](https://discourse.processing.org/u/CAVUCO)\
**Post date:** [November 25, 2020, 7:14pm UTC](https://discourse.processing.org/t/error-on-loadxml-url-within-p5js/25709/4 "2020-11-25T19:14:29Z")

</div>

Yes, I saw that link before and tried copying and pasting (substituting my url for his being careful to remove the https:// as that appears to be concatenated onto the string passed in the loadXML command.), and still did not work. Still get the error on line 56.

I used the same proxy as he. Any benefit going to a different proxy. Its just an ASCII response, don’t understand why a proxy is necessary and not documented within the p5.js reference material. Did have to make changes tot he index.html file?

---

<div class="post-metadata">

**Author:** ![CAVUCO](https://avatars.discourse-cdn.com/v4/letter/c/a9a28c/32.png) [@CAVUCO](https://discourse.processing.org/u/CAVUCO)\
**Post date:** [November 25, 2020, 7:24pm UTC](https://discourse.processing.org/t/error-on-loadxml-url-within-p5js/25709/5 "2020-11-25T19:24:28Z")

</div>

```auto
/**
 * loadXML() from EkstraBladet via Proxy (v2.0)
 * Andreas_Ref & GoToLoop (2019-Feb-08)
 *
 * https://Discourse.Processing.org/t/issue-loading-xml-feed-in-p5js/8212/2
 *
 * https://Bl.ocks.org/GoSubRoutine/5bdec67b4f70080bfddb6c0607cb6c70
 *
 * https://EkstraBladet.dk/rssfeed/sport/
 * https://Gist.GitHub.com/jimmywarting/ac1be6ea0297c16c477e17f8fbe51347
*/

"use strict";

const HTTP = 'https://',
      PROX = 'YaCDN.org/', MODE = 'proxy/',
      SITE = 'www.aviationweather.gov/adds/dataserver_current/httpparam?dataSource=metars&requestType=retrieve&format=xml&minLat=25&minLon=-125&maxLat=50&maxLon=-66&hoursBeforeNow=1&stationstring=K*&fields=station_id,latitude,longitude,flight_category', FOLD = 'rssfeed/', QRY = 'sport/',
      LINK = HTTP + PROX + MODE + HTTP + SITE,
      FILE = 'sport.xml',
      REMOTE = true,
      TAG = 'title',
      LIST = 'ol', ITEM = 'li',
      titles = [];

let xml;

function preload() {
  console.info(LINK);
  xml = loadXML(REMOTE && LINK || FILE, print, console.warn);
}

function setup() {
  noCanvas(), noLoop();

  const items = xml.getChild('data').getChildren('METAR');

  for (const item of items) {
    print(item.listChildren());
    //titles.push(item.getChild(TAG).getContent());
  }

  
}

```

Same error

---

<div class="post-metadata">

**Author:** ![GoToLoop](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/gotoloop/32/86_2.png) [@GoToLoop](https://discourse.processing.org/u/GoToLoop)\
**Post date:** [November 26, 2020, 1:24am UTC](https://discourse.processing.org/t/error-on-loadxml-url-within-p5js/25709/6 "2020-11-26T01:24:14Z")

</div>

I did some experiments and I’ve found this proxy link works:  
[https://YaCDN.org/proxy/https://www.AviationWeather.gov/adds/dataserver\_current/httpparam?dataSource=metars&requestType=retrieve&format=xml&stationstring=KSE\*&hoursBeforeNow=1&minLat=25&minLon=-125&maxLat=50&maxLon=-66&fields=station\_id,latitude,longitude,flight\_category](https://YaCDN.org/proxy/https://www.AviationWeather.gov/adds/dataserver_current/httpparam?dataSource=metars&requestType=retrieve&format=xml&stationstring=KSE*&hoursBeforeNow=1&minLat=25&minLon=-125&maxLat=50&maxLon=-66&fields=station_id,latitude,longitude,flight_category)

But if we shorten `KSE*` to `KS*` it stops working:  
[https://YaCDN.org/proxy/https://www.AviationWeather.gov/adds/dataserver\_current/httpparam?dataSource=metars&requestType=retrieve&format=xml&stationstring=KS\*&hoursBeforeNow=1&minLat=25&minLon=-125&maxLat=50&maxLon=-66&fields=station\_id,latitude,longitude,flight\_category](https://YaCDN.org/proxy/https://www.AviationWeather.gov/adds/dataserver_current/httpparam?dataSource=metars&requestType=retrieve&format=xml&stationstring=KS*&hoursBeforeNow=1&minLat=25&minLon=-125&maxLat=50&maxLon=-66&fields=station_id,latitude,longitude,flight_category)

Much probably b/c the request above bacame too big now for the proxy server.

However w/ this other proxy server it doesn’t care much about the request’s size; even `K*` is OK:  
[https://CORS-Anywhere.HerokuApp.com/https://www.AviationWeather.gov/adds/dataserver\_current/httpparam?dataSource=metars&requestType=retrieve&format=xml&stationstring=K\*&hoursBeforeNow=1&minLat=25&minLon=-125&maxLat=50&maxLon=-66&fields=station\_id,latitude,longitude,flight\_category](https://CORS-Anywhere.HerokuApp.com/https://www.AviationWeather.gov/adds/dataserver_current/httpparam?dataSource=metars&requestType=retrieve&format=xml&stationstring=K*&hoursBeforeNow=1&minLat=25&minLon=-125&maxLat=50&maxLon=-66&fields=station_id,latitude,longitude,flight_category)

P.S.: The URL above w/ this particular proxy only works when programmatically requested.

It won’t work by clicking or pasting it in a browser!

---

<div class="post-metadata">

**Author:** ![CAVUCO](https://avatars.discourse-cdn.com/v4/letter/c/a9a28c/32.png) [@CAVUCO](https://discourse.processing.org/u/CAVUCO)\
**Post date:** [November 26, 2020, 10:10pm UTC](https://discourse.processing.org/t/error-on-loadxml-url-within-p5js/25709/7 "2020-11-26T22:10:20Z")

</div>

I tried proxy and it worked for a while then it stopped working. Are they limited use proxies or something. I don’t understand still why we have to use a proxy. I can enter the url straight in a browser and it returns data.

---

<div class="post-metadata">

**Author:** ![GoToLoop](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/gotoloop/32/86_2.png) [@GoToLoop](https://discourse.processing.org/u/GoToLoop)\
**Post date:** [November 26, 2020, 10:37pm UTC](https://discourse.processing.org/t/error-on-loadxml-url-within-p5js/25709/8 "2020-11-26T22:37:29Z")

</div>

> [@CAVUCO](#):
>
> I tried proxy and it worked for a while then it stopped working.

Proxies aren’t meant for constant usage AFAIK.

The link still works on the proxy’s demo site though:  
[https://www.AviationWeather.gov/adds/dataserver\_current/httpparam?dataSource=metars&requestType=retrieve&format=xml&stationstring=K\*&hoursBeforeNow=1&minLat=25&minLon=-125&maxLat=50&maxLon=-66&fields=station\_id,latitude,longitude,flight\_category](https://www.AviationWeather.gov/adds/dataserver_current/httpparam?dataSource=metars&requestType=retrieve&format=xml&stationstring=K*&hoursBeforeNow=1&minLat=25&minLon=-125&maxLat=50&maxLon=-66&fields=station_id,latitude,longitude,flight_category)

[https://RobWu.nl/cors-anywhere.html](https://RobWu.nl/cors-anywhere.html)

> [@CAVUCO](#):
>
> I don’t understand still why we have to use a proxy.

B/c the site [AviationWeather.gov](http://AviationWeather.gov) doesn’t enable CORS for its API service:

> **[Cross-Origin Resource Sharing (CORS) - HTTP | MDN](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS)**
>
> Cross-Origin Resource Sharing (CORS) is an HTTP-header based mechanism that allows a server to indicate any origins (domain, scheme, or port) other than its own from which a browser should permit loading resources. CORS also relies on a mechanism by...

CORS is exclusive to browsers. A non-browser server can grab resources regardless of CORS.