Online calculator shows per-mile & total 5-mile run times based on mph in each mile

I've been doing the exercise wherein I go for a total of six miles, jogging the first third and fifth miles, and walking the second, fourth and sixth miles. I have gotten in the habit of noting the time it has taken me to go five miles after the fifth mile, as opposed to noting the time it has taken me to go six miles after six miles. This because during the sixth mile, I sometimes do things like stop in at a store to buy something.

Lately the weather has been so bad that I have been using the treadmill indoors. I noticed that the treadmill produces easy to notice and remember miles-per-hour and miles covered figures.

I felt I had to produce a computer program that would: translate mph for each mile into average mph for the total five miles; tell me the times each mile would be run in given the mph they are run in; and, give me the total time for the five miles given the various mph and times for each mile.

I felt such a program would help me to: set reasonable goals, be neither too ambitious or too cautious in terms of improving speed; and, motivate myself.

The computer program I envisioned and produced is now functioning in a page at:

http://www.aspserver444.qsh.eu/2tracktime.htm .

I wrote the program in javascript.