i have an array as , i need to remove the empty values and replace it with zeros.

i have achieved this much . when i checked the array length is 8 but it shows 2 elements only. What is the best method to replace it with zeros.

```
var a = [];

a[3] = 5

a[5] = 15

console.log(a.length) // 6

console.log(a) // [empty,empty,empty,5,empty,15] 

how can i make the output as [0,0,0,5,0,15]

```

// tried this way didn't worked 

```
a.map(o => o !== null ? o : 0)

```