XML file in Javascript, getElementByAttribute

Question

Let's suppose I have an XML file like this:

<?xml version="1.0" encoding="ISO-8859-1"?>
<MIDIFile>

  <Event>
    <Absolute>0</Absolute>
    <NoteOn Channel="1" Note="40" Velocity="64"/>
  </Event>
  <Event>
    <Absolute>236</Absolute>
    <NoteOff Channel="1" Note="40" Velocity="0"/>
  </Event>

</MIDIFile>

Thanks to some great tutorial I now know how to get these values in my javascript.

For example, I can iterate thru all the "Events" tag and get the "Absolute" value like this:

xmlhttp=new XMLHttpRequest();

xmlhttp.open("GET","test.xml",false);
xmlhttp.send();
xmlDoc=xmlhttp.responseXML;

// make an array with all the events from the xml file
var events = xmlDoc.getElementsByTagName("Event")


for (var i = 0; i<events.length; i++)
console.log(events[i].getElementsByTagName("Absolute")[0].childNodes[0].nodeValue)

this will return

0
236

Now, how the hell can I access the "NoteOn" attribute and get its values? I want to iterate thru all the Events in the XML, see if they contains NoteOn or NoteOff and load an array with all the notes, their duration, velocity and channels.

Please help me! getElementsByTagName("NoteOn") just doesn't work... If it might help, here are some screenshot of what happens if I console.log(xmlDoc)

Thanks a lot in advance!

screen

edit in response to an answer. As I try to do this:

var noteon = xmlDoc.getElementsByTagName('noteon');
console.log(noteon)

the result is just this one

[]

re-edit: If I write "NoteOn" instead of "noteon" it works!

Can you use jQuery? and what value of NoteOn do you want to extract? — gdoron
– gdoron, Commented May 23, 2012 at 23:19
He doesn't need jQuery it takes 4 lines of code or less to get the attributes. just as I have posted below. — Ryan
– Ryan, Commented May 23, 2012 at 23:26

Ryan · Accepted Answer · 2012-05-24 02:32:34Z

4

var noteon = xmlDoc.getElementsByTagName('noteon');
var note = new Array;
for(var i = 0; i < noteon.length; i++){
    note[i] = noteon[i].getAttribute('Note'); // or any of the attributes you want to get
}

Edit:

If noteon = [] then you have 2 options you can put the whole thing in a try catch, not the best thing to do in javascript, or you can put it in an if statement. Something like this should work:

var noteon = xmlDoc.getElementsByTagName('noteon');
var noteoff = xmlDoc.getElementsByTagName('noteoff');
var note = new Array;

if(noteon != []){
    for(var i = 0; i < noteon.length; i++){
        note[i] = noteon[i].getAttribute('Note'); // or any of the attributes you want to get
} else if(noteoff != []){
    for(var i = 0; i < noteoff.length; i++){
        note[i] = noteoff[i].getAttribute('Note'); // or any of the attributes you want to get
} else{
    return;  //makes sure the function returns to the call even if nothing was found
}
}

edited May 24, 2012 at 2:32

answered May 23, 2012 at 23:23

Ryan

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7 Comments

mistapink Over a year ago

He may wants all the Noteon or Noteoff within the events and not from the XML document.

Saturnix Over a year ago

it doesn't work, see edited answer. Thanks a lot anyway for your help!

Saturnix Over a year ago

Cool! It works if I write "NoteOn" instead of "noteon". Thanks a lot!

Saturnix Over a year ago

what if I try to access NoteOn inside of an event and it doesn't exist (because there is NoteOff and not NoteOn)? It trows error and stop the entire script :( I think I'll write a new question...

Ryan Over a year ago

@mistapink what do you mean? Noteon and noteoff are nodes of the xml document.

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