Odtnhj

I'm pretty new to JavaScript programming but I had experience in so many other programming languages. The idea of recursive functions in JavaScript is a fresh subject for me and I didn't see anything similar in other languages that I worked with. So for the sake of practicing, I decided to write some of the programs that I already have written with "for loops".

One of these programs is a function that takes a string as its argument and reports how many B letters are in it. Using objective-oriented programming, I first declared a function that can find the number of any other characters within a string. The program is as follows,

function countChar(string, char) 
 let counted = 0;
 for (let index = 0; index < string.length; index++) 
 if (string[index].toUpperCase() == char.toUpperCase()) 
 counted += 1;
 
 
 return counted;


function countBs(text) 
 return countChar(text, 'B');


console.log(countBs('Baby'));
// output = 2

It works very well but now that I'm using recursive functions, I get the "Maximum call stack size" error. My program with recursive functions looks like this one,

function countChar(string, char) 
 function cursor(i, counted) 
 if (i == string.length) 
 return counted;
 else if (string[i].toUpperCase() == char.toUpperCase()) 
 return cursor(i++, counted++);
 else 
 return cursor(i++, counted);
 
 
 return cursor(0,0);


function countBs(text) 
 return countChar(text, 'B');


console.log(countBs('Baby'));
// output must be 2 but I get 'Maximum call stack size' error instead :(

Can anybody offers a modification to this program in order to get the solution? Is it basically possible to write this program by using the recursive functions?

because

 return cursor(i++, counted++);

has to be

 return cursor(i + 1, counted + 1);

(as you want to increase the value passed recursively, not the local variable i)

How i would do that:

 const countBs = (str, i = 0) => 
 i >= str.length
 ? 0
 : countBs(str, i + 1) + (str[i].toUpperCase() === "B");

Or if you plan to use it for very very long strings, allow for TCO:

 function countBs(str, i = 0, count = 0) 
 if(i >= str.length) return count;
 return countBs(str, i + 1, count + (str[i].toUpperCase === "B"));