Return true if the passed string looks like a valid US phone number.

Write a function which takes a ROT13 encoded string as input and returns a decoded string.

Return true if the given string is a palindrome. Otherwise, return false. A palindrome is a word or sentence that's spelled the same way both forward and backward, ignoring punctuation, case, and spacing.

According to Kepler's Third Law, the orbital period T of two point masses orbiting each other in a circular or elliptic orbit is:

Create a function that sums two arguments together. If only one argument is provided, then return a function that expects one argument and returns the sum.

Check if the predicate (second argument) is truthy on all elements of a collection (first argument).

Return an English translated sentence of the passed binary string. The binary string will be space separated.

Given a positive integer num, return the sum of all odd Fibonacci numbers that are less than or equal to num.

Convert the characters &, <, >, " (double quote), and ' (apostrophe), in a string to their corresponding HTML entities.

Write a function that takes two or more arrays and returns a new array of unique values in the order of the original provided arrays. In other words, all values present from all arrays should be included in their original order, but with no duplicates in the final array.

freeCodeCamp Intermediate Algorithm Scripting: Arguments Optional