Referencing one array to make changes in another given certain conditions in JavaScript [closed]

Question

I have an array, called arr1, example [9, 0, 0 ,9, 9]. I made a copy of this and called it arr2. I am trying to add the value one (1) to certain indexes in arr2, dependent on the index position of arr1 and it being a nine (9).

For example,

if arr1[0] == 9, add one (1) to indexes [0], [3], [4] in arr2  
if arr1[3] == 9, add one (1) to indexes [0], [2], [3] in arr2  
if arr1[4] == 9, add one (1) to indexes [0], [1], [4] in arr2

So arr2 becomes [12, 1, 1, 11, 11].

Hope this makes sense, bear with me, I'm new to this.

Cheers.

Answer 1

The following code is what achieves your task.

var arr1 =  [9, 0, 0 ,9, 9];
         var arr2 = [...arr1]; // create a copy or a clone or array one
         if(arr1[0] == 9){
            arr2[0] += 1;
            arr2[3] += 1;
            arr2[4] += 1;            
         }

         if(arr1[3] == 9){          
            arr2[0] += 1;
            arr2[2] += 1;
            arr2[3] += 1;            
         }

         if(arr1[4] == 9){
            arr2[0] += 1;
            arr2[1] += 1;
            arr2[4] += 1;            
         }

         console.log(arr2)