From 0481f8305c8e215b5dcf90977b3b59c7d362fc16 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micka=C3=ABl=20V=C3=A9ril?= <mveril@irsamc.ups-tlse.fr>
Date: Thu, 22 Aug 2019 11:00:58 +0200
Subject: [PATCH] Use asynchronous programming to read data files

---
 index.html      | 12 +++++++-----
 scripts/data.js | 15 +++++++++------
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/index.html b/index.html
index 34f40b87..6b30f2c3 100644
--- a/index.html
+++ b/index.html
@@ -4,13 +4,15 @@
     <script src="scripts/data.js" type="text/javascript"></script>
     <script>
       function update_file(filename) {
-        lnk_doi=document.getElementById('lnk_doi');
         file=filename+'.json'
-        data=getDataFromFile(file)
-        lnk_doi.setAttribute('href',getDoiUrl(data));
-        lnk_file=document.getElementById('lnk_file');
         lnk_file.setAttribute('href',getFullDataPath(file));
-      }    
+        lnk_file=document.getElementById('lnk_file');
+        getDataFromFile(file,onApplyData)
+      }
+      function onApplyData(data) {
+        lnk_doi=document.getElementById('lnk_doi');
+        lnk_doi.setAttribute('href',getDoiUrl(data));
+      }
     </script>
     <script>
       window.onload=function() {
diff --git a/scripts/data.js b/scripts/data.js
index 4da18a84..c2a62b5b 100644
--- a/scripts/data.js
+++ b/scripts/data.js
@@ -1,13 +1,16 @@
-function getDataFromFile(file) {
+function getDataFromFile(file,fn) {
   var result = null;
   var xmlhttp = new XMLHttpRequest();
   xmlhttp
-  xmlhttp.open("GET",getFullDataPath(file), false);
-  xmlhttp.send();
-  if (xmlhttp.status==200) {
-    text = xmlhttp.responseText;
+  xmlhttp.open("GET",getFullDataPath(file), true);
+  xmlhttp.onreadystatechange = function() { 
+    if (this.readyState == 4 && this.status == 200) {//when a good response is given do this
+
+        var data = JSON.parse(this.responseText); // convert the response to a json object
+        fn(data)
+    }
   }
-  return JSON.parse(text);
+  xmlhttp.send();
 }
 
 function getDoiUrl(data) {