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View port Checker + Counting Numbers and Counting Progress bar ?

How can i use View port Checker for executing Counting Numbers and Counting Progress bar when they
view port of the screen?

I had counting numbers and counting progress bar on the middle of my page , the counting start when i load the page and when i scroll to reach it , they reach to it's final value , i want they to start counting when they on they on the port view screen ?