This JavaScript function will calculate the Golden Ratio of a given value.

function calculateGoldenRatio(width) {
  if (!width) {
    return {};
  }

  return {
    width: width,
    right: Math.round(width / 1.61803),
    total: Math.round(width * 1.61803),
    left:  width - Math.round(width / 1.61803)
  };
}

var gr = calculateGoldenRatio(920);
console.log(gr.left);  // 351
console.log(gr.right); // 569
console.log(gr.total); // 1489
console.log(gr.width); // 920