d3具有enter-update-exit逻辑的线图

today I created a simple Bar Chart with the enter-update-exit logic - everything works fine. Now I will do the same with a line chart - the whole dataset for the chart can change at any time, so I will update the chart smoothly. I can't find a good example with a line chart and the enter-update-exit logic (or I'm looking wrong). Currently I have to remember that if the chart is called for the first time or the data to be updated (data has changed) - This is my dirty version: today I created a simple Bar Chart with the ent