Pascal's Triangle

Pascal's Triangle

function triangle(num) {
  var result = [[1], [1,1]];

  for (var j = 0; j < num; j++) {
    // console.log('previousArr', result[result.length-1]);
    var previousArr = result[result.length-1];  
    var tempArr = [];
  
    // for each element of previous array
    for (var i = 0; i < previousArr.length ; i++) {
      
      // is this the 0 element?
      if (i === 0) {
        // Yes: push to temporary array
        tempArr.push(previousArr[i]);
        // result.push(i);
      } else if (i > 0 && i === previousArr.length-1) {
        // No: Add element and previous array element-1
        var sum = previousArr[i] + previousArr[i-1];
        //   push to temporary array
        tempArr.push(sum);
        tempArr.push(previousArr[previousArr.length-1]);
        result.push(tempArr);
      // No: Is this the last element of previous array?
      } else {
        var middleSum = previousArr[i] + previousArr[i-1];
        tempArr.push(middleSum);
      }
    }

    // is the result array length equal to the input number?
    if (result.length === num) {
      // Yes: Stop and return the result
      return result;
    }
    //  No: continue looping
  }
  
  return result;
}

console.log(triangle(7));