I'm developing a TypeScript app dealing with large size data. Once the primary data processing is over, I declared data as null so that the GC can process it.

But I guess the GC is not handled properly, so the JS heap size is not going down. To solve this problem, I want to know the exact meaning of the two charts of JS heap size (dark blue line and light blue line) in Performance monitor of Chrome DevTools.

Does the light blue chart is including data that GC cannot reach? From the calculation of the data size, I think the dark blue line is the right size if GC works well.

Here is a captured image of the performance monitor.

Thank you for taking your time for this question.