Javascript Caesar Cipher Algorithm

Is there anyway to do this function?, because i find it quite difficult to understand, specially that function with a char parammeter which i dont see where or how i use it. functi

Solution 1:

Let us have a look at String.replace's function definition:

str.replace(regexp|substr, newSubStr|function [, flags]);

In JavaScript, we can pass a replacement function to the String.replace function. How the arguments of the function is populated is described in this section of MDN article.

Basically:

• The first argument is the string that matches the whole expression (equivalent to $& in replacement string)
• Followed by the content of the capturing groups (equivalent to $n where n is positive number). There will be as many arguments as the number of capturing groups.
• Followed by offset of the main match
• And the last argument is the input string.

So whatever matched by /([a-z])/ig will be supplied to the replacement function as the first argument (char in this case). The character matched will be processed and returned as the replacement.

In your code, /([a-z])/ig can be simplified to /[a-z]/ig, since the replacement function only refers to the main match.