JS Canvas histogram Nothing high-end is an occasional thought

Company project to use JS to draw a histogram, originally wanted to use a plug-in bar chart.js suddenly think we can not use so big plug-ins, write a bar, you can also see their point of math level can not!

There's a few little highlights.

1. function x and function y convert coordinates if the upper left corner of the canvas is the origin, that's a lot of pit-daddy.

2. Draw the rectangle with a thick line, ah, the rectangle that the four points is really killing Ah, or draw line really!

Give a shot, big God don't spray!

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JS Canvas histogram Nothing high-end is an occasional thought