How to calculate the start and end points of the regression line, which should be set at the beginning and end of the chart (see screenshot)?

Question

JavaScript

the left and right ends of the line should continue to the edges of the graph. I can't figure out what formula to use for this.
chart is built in js with chart.js

Answer 1

The line is y = ax+b, where the parameters are found from minimizing the sum of squared differences (y - Yi).