Find the perpendicular line from a line AB to point C using Turf JS

slopeIx.js

function slopeIx(a, b, c) {
 //GET POINT OF X AND Y INTERCEPT FROM POINT C AND LINE AB
 const lines = turf.featureCollection([]);
 const bearing1 = turf.bearing(a, b);
 const slope = (b[1] - a[1]) / (b[0] - a[0]);
 const point1 = [c[0], slope * (c[0] - a[0]) + a[1]];
 const point2 = [(c[1] - a[1]) / slope + a[0], c[1]];
 const lineArray = [a, b, point1, point2];

 //NORMALIZE LINE
 lineArray.sort((a, b) => b[0] - a[0]);
 lines.features.push(turf.lineString(lineArray));

 //CREATE 90DEG LINE FROM POINT C TO LINE AB
 const { geometry: p90 } = turf.destination(
  turf.point(c),
  //THE DISTANCE A TO C WILL ALWAYS BE LARGER THAN THE DISTANCE FROM C TO THE EXTENDED LINE AB
  turf.distance(a, c),
  bearing1 + 90
 );
 const { geometry: p91 } = turf.destination(
  turf.point(c),
  turf.distance(a, c),
  bearing1 - 90
 );
 const pline = turf.lineString([p90.coordinates, p91.coordinates]);
 lines.features.push(pline);

 //GET INTERSECTING POINT 90DEG FROM POINT C TO EXTENDED LINE AB
 const intersectingPoint = turf.lineIntersect(
  lines.features[0],
  lines.features[1]
 );

 //GET THE DISTANCE FROM THE INTERSECTING POINT TO POINT C
 const distance = turf.distance(intersectingPoint.features[0], turf.point(c), {
  units: "miles"
 });

 return { distance, intersectingPoint, lines }
}