discourse/app/assets/javascripts/admin/helpers/value-at-tl.js.es6

import { registerUnbound } from 'discourse/lib/helpers';

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