OpenLayers Autoincrement ID for drawing features

Question

I have the features drawn manually in OpenLayers. Since I have managed to set the properties for my drawings, i.e. by this thread:

OpenLayers problem with adding features to custom drawings

I would like also to have the autoincrement ID.

I found a nice example here:

https://embed.plnkr.co/plunk/NgIpC3

which pretty much shows how to do it, although the GetID() appears only once in this code.

My full code looks like this now:

 var lineInteraction = new ol.interaction.Draw({
 type: 'LineString',
 source: vectorLayer.getSource()
 });
 lineInteraction.setActive(false);
 lineInteraction.on('drawend', onDrawend);
 lineInteraction.on('drawend', function(e) {
 var title = prompt("Please provide the data", "untitled");
 var value = prompt("Please provide the value", "undefinied");
 e.feature.setProperties({
  'Id': GetID(),
  'Name': title,
  'Value': value,
   });
 });

I am getting an error from my console that:

ReferenceError: GetID is not defined

I just need to increment my ID.

As per the example:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Increment

https://stackoverflow.com/questions/11026258/html-and-javascript-auto-increment-number

I tried to set the new variable and then assign it to my 'ID', although it throws ID 1 only

 var lineInteraction = new ol.interaction.Draw({
 type: 'LineString',
 source: vectorLayer.getSource()
 });
  lineInteraction.setActive(false);
  lineInteraction.on('drawend', onDrawend);
  lineInteraction.on('drawend', function(e) {
  var title = prompt("Please provide the data", "untitled");
  var value = prompt("Please provide the value", "undefinied");
  let x = 1
  var id = x++
  e.feature.setProperties({
  'Id': id,
  'Name': title,
  'Value': value,
   });
  });

How can I make an autoincrement the ID of my drawing feature in OpenLayers?

Answer 1

   var idn ;
      function GetID(idn ){
    var tt = idn;
       tt++;
     return tt;
    }

 var lineInteraction = new ol.interaction.Draw({
 type: 'LineString',
 source: vectorLayer.getSource()
 });
 var idt=0;
 lineInteraction.setActive(false);
 lineInteraction.on('drawend', onDrawend);
 lineInteraction.on('drawend', function(e) {
 var title = prompt("Please provide the data", "untitled");
 var value = prompt("Please provide the value", "undefinied");
 e.feature.setProperties({
  'Id':  GetID(idt++),
  'Name': title,
  'Value': value,
   });
 });