代码重构。 试图改进我的代码

Question

My code passed, no problem. But I would like your guys opinion as to what I could have improved in my code. Unnecessary things, tips, better ways to do the same thing, faster ways, I'm literally open to any kind of feedback. Lately I'm only trying to focus on improve how fast I can solve a problem, and this one, took me almost 5 hours. This code comes from the 2D Array HourGlass. My thought process was to makeup a model of what I wanted, than for loop through the lines and rows, and that's how I came with this result. Also, I wanted to improve from thinking of WHAT the code should do, other than HOW. It's hard, but any tips I would really appreciate. Since I'm coding only Front End stuff, my solving problems is literally shit.
Thanks !

function hourglassSum(arr) {

        let newInput = arr
        let arrAnswer = []

        for(let line in newInput){
            for (let row in newInput){
                let newRow = parseInt(row)
                let newLine = parseInt(line)
                if(newLine < 4){
                    let a =newInput[newLine +0][newRow]
                    let b =newInput[newLine +0][newRow+1]
                    let c =newInput[newLine +0][newRow+2]
                    let d =newInput[newLine +1][newRow+1]
                    let e =newInput[newLine +2][newRow]
                    let f =newInput[newLine +2][newRow+1]
                    let g =newInput[newLine +2][newRow+2]
                    if(a,b,c,d,e,f,g == undefined){
                        break
                    }
                    arrAnswer.push([a,b,c,d,e,f,g].reduce((item1,item2)=> item1 + item2, 0))
                }
            }
        }

        let answer = arrAnswer.reduce((item1, item2) => (item1 > item2 ) ? item1: item2 )

        return answer 

    }

Answer 1

if(a,b,c,d,e,f,g == undefined) Are you expecting this to check if any of your 7 values are undefined?

Based on the comma operator specs I believe it is only checking g == undefined .

The comma operator evaluates each of its operands (from left to right) and returns the value of the last operand.

If you really mean to check for any null values, here's one way you could do it

if([a,b,c,d,e,f,g].indexOf(undefined)>=0) ...

Answer 2

Your code has a lot of redundancies:

let newInput = arr

Unnecessary.

let answer = arrAnswer.reduce((...

Stuffing it in a var is unnecessary, since you just return it on the next line.

As far as I can tell, your entire code can be changed to the following:

const hourglassSum = input => {
  return input
    .map((a, i, arr) => { // NEVER use for..in with arrays. Use .map or for..of
      return arr.map(b => {
        const idx1 = parseInt(a, 10); // always use radix
        const idx2 = parseInt(b, 10);

        // Use boolean short-circuiting, we'll filter later.
        // Your original code had potentially error throw here
        // if the first access resulted in undefined.
        const intermediate = input[idx1] !== undefined &&
          input[idx1 + 1] !== undefined &&
          input[idx1 + 2] !== undefined &&
          [
            input[idx1][idx2],
            input[idx1][idx2 + 1],
            input[idx1][idx2 + 2],
            input[idx1 + 1][idx2 + 1],
            input[idx1 + 2][idx2],
            input[idx1 + 2][idx2 + 1],
            input[idx1 + 2][idx2 + 2],
          ];

        // boolean again, check to make sure we don't pollute the
        // arithmetic 
        return intermediate &&
          intermediate.every(x => x !== undefined) &&
          intermediate;
      })
      .filter(x => x) // weed out falses
      .reduce((a, b) => a + b, 0); // sum to int
    })
    .reduce((a, b) => Math.max(a, b)); // Math.max replaces ternary
};

This is arguably more readable, definitely less error prone, slightly shorter, makes better use of the built-ins like Math.max and the array methods. Is also consistent rather than mixing functional style with loops. One thing it isn't is faster, but you make it correct first, then fast.