Nested code - blocks of code inside blocks of code - is eventually necessary, but increases complexity. This is why keeping the code as flat as
possible, by avoiding unnecessary nesting, is considered a good practice.
Merging if statements when possible will decrease the nesting of the code and improve its readability.
Code like
if (x != undefined) {
if (y === 2) {
// ...
}
}
Will be more readable as
if (x != undefined && y === 2) {
// ...
}
