Epoch.js: Epoch is a general purpose charting library for application developers and visualisation designers. It focuses on two different aspects of visualisation programming: basic charts for creating historical reports, and real-time charts for displaying frequently updating time series data. I felt this one is good for real time charts.
I have found some more libraries which I am still exploring, So I have just listed below
If I have missed out any library or there is any references, please mention it in the comment section.