Cubic Bezier Curve function from control points

CubicBezierCurve.js

/**
 * Create cubic bezier curve function from 4 points
 *
 * @param {Plain Object} p0 : start point
 * @param {Plain Object} p1 : first control point
 * @param {Plain Object} p2 : second control point
 * @param {Plain Object} p3 : end point
 */
function BezierCubicXY(p0, p1, p2, p3){
    this.coords = ['x', 'y'];
    this.p0 = p0;
    this.p1 = p1;
    this.p2 = p2;
    this.p3 = p3;
}
BezierCubicXY.prototype.xy = function(t) {
    var _me = this,
        ret = {};

    _me.coords.forEach(function(k){
        ret[k] = Math.pow(1 - t, 3) * _me.p0[k] + 3 * Math.pow(1 - t, 2) * t * _me.p1[k] + 3 * (1 - t) * Math.pow(t, 2) * _me.p2[k] + Math.pow(t, 3) * _me.p3[k];
    })

    return ret;
}

// Usage
console.log('BezierCubicXY', (new BezierCubicXY({x: 225, y: 100}, {x: 132.5, y: 100}, {x: 132.5, y: 20}, {x: 40, y: 20})).xy(0.5))