How to find the point of intersection of two segments?

Question

JavaScript

Hello Habr!
Since I am a noob in geometry, I ask you to help with one case:
I have 4 points, these are two points of the beam (beginning and direction) and two points of the segment. I need, given these four points, to find the point of their intersection (and also to find out if they intersect at all). Very much I ask to result function for a finding. Function type:

const getCollisionPoint = (r1, r2, s1, s2) => ...
// где r1 и r2 - точки луча([x1, y1] и [x2, y2]),
// а s1 и s2 - точки отрезка([x3, y3] и [x4, y4])

Answer 1

It is done in three simple steps:
1. write the equations of the lines on which the segments lie
2. find the point of intersection of the lines: https://www.google.com/search?q=intersection+of the lines...
3. determine if this line lies point within lines

Very much I ask to result function for a finding.

Then it will be a task, not a question. This is removed by the moderators - okay?