Let A, B, C and D be four points in the plan. Then of the pair of angles ABC and ABD, determine which is larger.

  C
  *      D
   \     *
    \ABC/
     \ / ABD
      *-------------*
      B             A

var compareAngle = require("compare-angle")

var A = [2, 0]
var B = [0, 0]
var C = [-1, 2]
var D = [1, 1]

console.log(compareAngle(A, B, C, D),  compareAngle(A, B, D, C))

Output:

1   -1

npm install compare-angle

Compares the angles ABC and ABD to determine which is greater.

• a, b are the base points of the angle
• c is the end of the first angle
• d is the end of the second angle

Returns A number indicating which angle is larger

• +1 if angle ABC is greater than angle ABD
• 0 if the angles are equal
• -1 if angle ABD is greater than angle ABC

(c) 2014 Mikola Lysenko. MIT License