How to use JavaScript to retrieve a html element that is also created in JavaScript

Question

The html buttons are created in JavaScript, each with their own ID. They activate the same function when pressed, and I want to know which button is pressed. I use this.id to see the ID of the button pressed. I think, since I haven't retrieved the buttons in JavaScript (eg. button = document.getElementById('button')), it doesn't work. I don't know how to do this with HTML elements created inside the script.

var paragraph = document.getElementById('paragraph');

var cabins = [1,2,3];

for (var i = 0; i < cabins.length; i++) {
  paragraph.innerHTML += "Cabin " + cabins[i] + "<br><br><button id='cabin" + cabins[i] +"' onclick='purchaseCabin()'>Purchase</button><br><br>"
}

function purchaseCabin() {
  var cabinId = this.id;
  console.log(cabinId);
}

<p id="paragraph"></p>

Expected result: the ID of the pressed button is written in the console

Actual result: "undefined" is written in the console

Answer 1

this inside the function refers to Window which does not have the property id, thus you get undefined:

Pass this object to the function so that you can refer that inside the function:

var paragraph = document.getElementById('paragraph');
var cabins = [1,2,3];
for (var i = 0; i < cabins.length; i++) {
  paragraph.innerHTML += "Cabin " + cabins[i] + "<br><br><button id='cabin" + cabins[i] +"' onclick='purchaseCabin(this)'>Purchase</button><br><br>"
}

function purchaseCabin(current) {
  //console.log(this.constructor.name); // Window
  var cabinId = current.id;
  console.log(cabinId);
}

<p id="paragraph"></p>