在添加元素时循环遍历数组中所有元素的最有效方法

Question

I have a 2d array in Google Apps Script Javascript. I'm trying to loop through all elements but one of the loop options is adding another element. So for example:

for (let i in arr){
  if (arr[i][0] == "good")
    arr[i].push("clear");
  else if (arr[i][0] == "add")
    arr.splice(+i+1,0,"good");
}

But then it's not going through the actual end of the code, I presume because "let i in arr" is getting the leght of the array once and going to that end. This is causing later issues. Should I use a while or do while loop instead? Should I declare a length value and increase it manually whenever an element gets added?

Answer 1

Use arr.length in your condition and it will check against the most up-to-date array length.

for (let i = 0; i < arr.length; i++) {
  if (arr[i][0] == "good")
    arr[i].push("clear");
  else if (arr[i][0] == "add")
    arr.splice(+i+1,0,"good");
}