Flatten Array
Problem : Implement a function flatten that returns a newly-created array with all sub-array elements concatenated recursively into a single level. Solution: const results = []; function flatten ( array ) { if ( Array . isArray ( array )) { array . forEach (( element ) => { if ( Array . isArray ( element )) { flatten ( element ); } else { results . push ( element ); } }); } return results ; } console . log ( flatten ([ 1 , 2 , 3 , [ 5 , 6 , [ 8 , 9 ]], 23 ])); // [1, 2, 3, 5, 6, 8, 9, 23]
