Reasonable d3.js (v4) update logic

index.js

 _updated3 : function (canvas, data) {
    // JOIN data to canvas and provide selection object
    const circlesSelection = canvas.selectAll("circle").data(data);

    // get circles which have to be added and subtracted
    const circlesToAdd = circlesSelection.enter();
    const circlesToRemove = circlesSelection.exit();

    // create and delete svg object
    const newCricles = circlesToAdd.append(d3.creator("circle"));
    const obsoleteCircles = circlesToRemove.remove();

    // get currently visible circles
    const currentCircles = newCricles.merge(circlesSelection);
 }