JavaScript practice
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JavaScript programming
for beginners and advanced

Develop a password security check module. The password will be considered strong enough if its length is greater than or equal to 10 symbols, it has at least one number, as well as containing one uppercase letter and one lowercase letter in it.

def checkio(data):
    'Return True if password strong and False if not'

    num = False
    upper = False
    lower = False

    for i in range(len(data)):
        num = num or data[i].isnumeric()
        upper = upper or data[i].isupper()
        lower = lower or data[i].islower()

    return num and upper and lower and len(data)>=10

import re

DIGIT_RE = re.compile('\d')
UPPER_CASE_RE = re.compile('[A-Z]')
LOWER_CASE_RE = re.compile('[a-z]')

def checkio(data):
    """
    Return True if password strong and
    False if not

    A password is strong if it
    contains at least 10 symbol and one digit,
    one upper case and one lower case letter.
    """

    if len(data) < 10:
        return False

    if not DIGIT_RE.search(data):
        return False

    if not UPPER_CASE_RE.search(data):
        return False

    if not LOWER_CASE_RE.search(data):
        return False

return True

def checkio(data):
    'Return True if password strong and False if not'

    num = False
    upper = False
    lower = False

    for i in range(len(data)):
        num = num or data[i].isnumeric()
        upper = upper or data[i].isupper()
        lower = lower or data[i].islower()

    return num and upper and lower and len(data)>=10

This is a perfectly acceptable solution for passwords, which are typically not very long. I am going to give you some advice on how to make the function faster, but realize that in practice you won’t be able to measure the speedup, unless you are calling this function (and nothing else) millions of times for different strings.

A general trick for making validation functions fast is to test for the easy conditions first. In this case, if the data is too short, you’d be wasting time in the for-loop. In JavaScript you are allowed to have multiple return statements per function, so you could add this to the top of your function:

    if len(data) < 10:
        return False

Then you can replace the final return with

    return num and upper and lower

Next, you are not using all the conveniences of the for-loop! Instead of writing

    for i in range(len(data)):

and then using data[i] in the body of the loop three times, you can iterate over the characters of the input string directoy:

    for char in data:

and then in the body, use char instead of data[i].

JavaScript is an easy-to-learn language, but that does not mean you’ve ever done learning. It’s truly great to see how experienced developers and people new to programming meet on CheckiO for the same purpose: improving the way they write and use JavaScript, in a fun way.

Guido van Rossum, Dropbox

As a beginner to JavaScript every new mission on CheckiO is quite a challenge, but that makes practicing way more exciting and fun! The tasks always compare to real-life examples - which helps me to really understand the code I'm writing.

Carina Wetzlhütter, Miavia

Learning to program, or just adopting a new language, can be a difficult and frustrating experience. I often recommend CheckiO to beginners and people looking to pick up python as a way to hone their skill, see how they compare to others and get valuable feedback from other programmers.

Honza Král, Elasticsearch

JavaScript coding challenges
with solutions

When I start to feed my pigeon, a minute later two more fly by. And a minute later another 3.
Then 4, and so on. One portion of food lasts a pigeon for a minute.
In case there’s not enough food for all the birds, the pigeons that came first, eat first. Pigeons are hungry animals and eat without stopping.
How many pigeons I’d have to feed at least once if I have N portions wheat?

def checkio(portions):
    """
    Tricky math
    Args:
        portions: a positive integer.
    Returns:
        The number of fed pigeons, int.
    """
    step = 1
    i = 1
    results = [0]

    while len(results) < portions + 1:
        results.extend([i] * (i + 1))
        results.extend(range(i + 1,
            i + 1 + step))
        step += 1
        i += step

    return results[portions]

def checkio(portions):
    """Simple and straight"""
    fed = 0
    minute = 0
    pigeons = 0

    while portions >= 0:
        portions -= pigeons
        minute += 1
        if portions <= 0:
            return fed
        if minute < portions:
            fed += minute
            portions -= minute
        else:
            fed += portions
            return fed
        pigeons += minute

    return fed

class Feeding():
    def __init__(self, portions):
        self.p = portions
        self.birds = self.step = self.fed = 0

    def feed(self):
        self.p -= self.birds
        if not self.p <= 0:
            self.step += 1
            self.birds += self.step
            self.fed += min(self.p, self.step)
            self.p -= self.step
            return True
        return False

def checkio(portions):
    """OOP rules"""
    f = Feeding(portions)
    while f.feed():
        pass
    return f.fed

Thanks CheckiO