I have come across a problem while fetching data from an external XML document with JS. I have been following the w3schools tutorial for AJAX XML so far, but I ran into something I couldn't solve. I have a XML that looks like this:
<root>
<document-id>
<author>Tom Riddle</autor>
<title>abzy</title>
<year>1995</year>
</document-id>
<document-id>
<author>Tom Riddle</autor>
<title>abzy</title>
</document-id>
<document-id>
<author>Tom Riddle</autor>
<year>1995</year>
</document-id>
</root>
I want to dynamically access the data inside the XML and create a table while doing so. It works fine for the one DOM Element all documents share, but it gives me an error as soon as I include year or title. I guess it's because the tags are empty in some parts of the tree. Is there a way to ignore empty tags and only write something in the column if there is a value inside? Thank you for your time and knowledge.
THIS IS THE ASSOCIATED HTML
<body>
<header>
<h1>Reading Data from XML Files</h1>
</header>
<main>
<button type="button" onclick="loadDoc()">Get my CD collection</button>
<table id="demo">
</table>
</main>
<script>
function loadDoc() {
const xhttp = new XMLHttpRequest();
xhttp.onload = function() {
myFunction(this);
}
xhttp.open("GET", "books.xml");
xhttp.send();
}
function myFunction(xml) {
const xmlDoc = xml.responseXML;
const x = xmlDoc.getElementsByTagName("document-id");
console.log(x)
let table="<tr><th>Author</th><th>Title</th><th>Year</th></tr>";
for (let i = 0; i <x.length; i++) {
table += "<tr><td>" +
x[i].getElementsByTagName("author")[0].childNodes[0].nodeValue +
"</td><td>" +
x[i].getElementsByTagName("title")[0].childNodes[0].nodeValue +
"</td><td>" +
x[i].getElementsByTagName("year")[0].childNodes[0].nodeValue +
"</tr>";
}
document.getElementById("demo").innerHTML = table;
}
</script>
</body>
Check for existence before you try to access the children.
function getText(node, tag) {
var elem = node.getElementsByTagName(tag);
return elem ? elem.[0].childNodes[0].nodeValue : '';
}
for (let i = 0; i <x.length; i++) {
var cells = ['author', 'title', 'year'].map(function (tag) {
return "<td>" + getText(x[i], tag) + "</td>";
}).join("");
table += "<tr>" + cells + "</tr>");
}
try this with in line solution to check if tag exist in xml
function myFunction(xml) {
const xmlDoc = xml.responseXML;
const x = xmlDoc.getElementsByTagName("document-id");
console.log(x)
let table="<tr><th>Author</th><th>Title</th><th>Year</th></tr>";
for (let i = 0; i <x.length; i++) {
table += "<tr><td>" +
x[i].getElementsByTagName("author")[0].childNodes[0].nodeValue +
"</td><td>" + ((x[i].getElementsByTagName("title")[0] == undefined)?"": x[i].getElementsByTagName("title")[0].childNodes[0].nodeValue ) +
"</td><td>" +
((x[i].getElementsByTagName("year")[0] == undefined)?"": x[i].getElementsByTagName("year")[0].childNodes[0].nodeValue ) +
"</tr>";
}
document.getElementById("demo").innerHTML = table;
}