gleb-mihalkov

function getLineFn(x1, y1, x2, y2) {
  
  var k = (y2 - y1) / (x2 - x1);
  var b = y1 - k * x1;

  return function(x, y) {
    var f = x * k + b;
    var d = Math.abs(y - f);
    return d < 0.00001;
  }
}

var x1 = 10
var y1 = 10
var x2 = 500
var y2 = 400

var isOnLine = getLineFn(x1, y1, x2, y2);
var test = isOnLine(100, 200);
console.log(test);