Generally, it is a good start for functional programming newcomers. Nonetheless, I think it should have contained more examples.

Hi Luisa, Thanks for the nice and concise writing about functional programming. By the way in your string example, I think there is a small typo. Instead of const hi = "hi guys" ; It should be const str = "hi guys" ;

"For god's sake please don't write your own date formatting/parsing functions." Every time you do it, a pupil dies somewhere in the world :(

Thank you for your kind comment Erry. Glad you like :)

Hey Yogesh Chavan Good tips thanks. By the way, I can add my two cents to your article. In getting the last element of the array section, in the first example arr.slice(-1) will return [50] not the value 50 . For checking if it is an array I guess we can also use below code const isArray = Object .prototype.toString.call(arr) == "[object Array]"

You can check your second parameter as below without 0 trap. if (b != undefined) { // if b provided return a * b; }

In Mutation Bad section assignment operation must be done with index 1. Nice work by the way. const code= [ "Javascript", "Python", "React" ] code[ 1 ] = "Node"