PascalTriangle.js

const addRow = (triangle) => {
 const previous = triangle[triangle.length - 1]
 const newRow = [1]
 for (let i = 0; i < previous.length - 1; i++) {
 const current = previous[i]
 const next = previous[i + 1]
 newRow.push(current + next)
 }
 newRow.push(1)
 return triangle.push(newRow)
}

const generate = (numRows) => {
 const triangle = [[1], [1, 1]]

 if (numRows === 0) {
 return []
 } else if (numRows === 1) {
 return [[1]]
 } else {
 for (let i = 2; i < numRows; i++) {
 addRow(triangle)
 }
 }
 return triangle
}

export { generate }