Array comprehensions are a convenient, declarative form for creating computed arrays with a literal syntax that reads naturally.
Per iterators, default property value (not key) enumeration and custom value iteration may be done using
for-of loop head syntax, rather than
Filtering an array:
[ x for (x of a) if (x.color === ‘blue’) ]
Mapping an array:
[ square(x) for (x of [1,2,3,4,5]) ]
[ [i,j] for (i of rows) for (j of columns) ]