Solution.js

const generate = function(numRows){
  let arr = [];
  for(let i = 0; i < numRows; i++){
    let row = [];
    row[0]=1;
    row[i] = 1;
    for(let j = 1; j < row.length - 1; j++){
      row[j] = arr[i-1][j-1] + arr[i-1][j];
    }
    arr.push(row);
  }
  return arr;
}

/** 
 *  Author: Mcnwork2018
 */

var generate = function(numRows) {
  if (numRows === 0) return [];
  if (numRows === 1) return [[1]];
  if (numRows === 2) return [[1],[1,1]];
  let triangleArray = [[1],[1,1]];
  for ( let i = 2; i < numRows; ++i ) {
    triangleArray[i] = [];
    for ( let j = 0; j < i + 1; ++j ) {
      if ( j === 0 || j === i ) {
        triangleArray[i][j] = 1;
      } else {
        triangleArray[i][j] = triangleArray[i-1][j-1] + triangleArray[i-1][j];
      }
    }
  }
  return triangleArray;
};