3.3 Bean Counting (Eloquent JavaScript Solutions)

3-3 Eloquent Javascript Solutions.js

function countBs(s) {
  var count = 0; 
  for (var i = 0; i < s.length; i += 1) {
    if (s.charAt(i) === "B")
      count += 1;
  }
  return count;
}

function countChar(s, c) {
  var count = 0; 
  for (var i = 0; i < s.length; i += 1) {
    if (s.charAt(i) === c)
      count += 1;
  }
  return count;
}

console.log(countBs("BBC"));
// → 2
console.log(countChar("kakkerlak", "k"));
// → 4

3.3. Bean counting

You can get the Nth character, or letter, from a string by writing "string"[N]. The returned value will be a string containing only one character (for example, "b"). The first character has position zero, which causes the last one to be found at position string.length - 1. In other words, a two-character string has length 2, and its characters have positions 0 and 1.

Write a function countBs that takes a string as its only argument and returns a number that indicates how many uppercase “B” characters there are in the string.

Next, write a function called countChar that behaves like countBs, except it takes a second argument that indicates the character that is to be counted (rather than counting only uppercase “B” characters). Rewrite countBs to make use of this new function.

Hints

Your function will need a loop that looks at every character in the string. It can run an index from zero to one below its length (< string.length). If the character at the current position is the same as the one the function is looking for, it adds 1 to a counter variable. Once the loop has finished, the counter can be returned.

Take care to make all the bindings used in the function local to the function by using the let keyword.

thanks man, needed that. especially the countBs. Cuz in the solution it was already rewritten.

hey! not sure if you will see this but may i ask why the counter has to be written outside of the for loop? i got it wrong cause my counter was inside the for loop :(

^ referring to var count = 0;

Hey @umpavi
If you declare the count variable within the for loop then it will reset to zero with every iteration of the loop.
By declaring count outside the for loop and setting the initial value to zero it can be incremented within the loop.
It's all about scope.
Variables declared within a code block (e.g. the for loop) have a different scope to those declared outside the block.

Thank you so much for that clarification. I understand it now and I really appreciate it! I'm new to JS and programming in general, and I don't really know people I can ask for help when I'm stuck so it's really nice to see people out there who are willing to help! Thank you and have a great day!

function countChar(s, c) {
var count = 0;
for (var i = 0; i < s.length; i += 1) {
if (s.charAt(i) === c)
count += 1;
}
return count;
}
function countBs(s){
return countChar(s,"B");
}
console.log(countBs("BBC"));
// → 2
console.log(countChar("kakkerlak", "k"));
// → 4