discourse/app/assets/javascripts/admin/addon/helpers/value-at-tl.js

import { registerUnbound } from "discourse-common/lib/helpers";

registerUnbound("value-at-tl", function (data, params) {
  let tl = parseInt(params.level, 10);
  if (data) {
    let item = data.find(function (d) {
      return parseInt(d.x, 10) === tl;
    });
    if (item) {
      return item.y;
    } else {
      return 0;
    }
  }
});