JavaScript, Python, Ruby: Filter()

filter string length in three dynamic languages

JavaScript (ES6)

filter() method iterates through an array and returns all strings which match the conditional expression. In this case, they should match x.length === 4.

const friend = a => a.filter(x => x.length === 4)

Node REPL

> a = ["Ryan", "Kieran", "Mark"]
[ 'Ryan', 'Kieran', 'Mark' ]
> a.filter(x => x.length === 4)
[ 'Ryan', 'Mark' ]

Python

Using a comprehension.

def friend(l): return [x for x in l if len(x) == 4]

Python REPL

>>> l = ["Ryan", "Kieran", "Mark"]
>>> l
['Ryan', 'Kieran', 'Mark']
>>> [x for x in l if len(x) == 4]
['Ryan', 'Mark']

Ruby

def friend a
  a.select { |x| x.length == 4 }
end

IRB REPL

irb(main):001:0> a = ["Ryan", "Kieran", "Mark"]
=> ["Ryan", "Kieran", "Mark"]
irb(main):002:0> a.select { |x| x.length == 4 }
=> ["Ryan", "Mark"]