Having trouble with specific function in javascript

Question

I have a question concerning javascript. I have created a function which prompts the user to enter a string, and once the string is entered will perform a for loop to go through the entire length of the string, looking for the character "B" and then return the number of "B"s found in the result variable. As far as my knowledge, I feel that the code I have should work, however not matter how many "B" are present within my code, the function consistently returns 2. Any ideas on why this would be happening

function countBs(string) {
    var result = 1;
    var string = prompt("Please Enter a String");
    for (count = 0; count < string.length; string++) {
        if (string.charAt(count) == "B") {
            result += 1;
            return result;
        }
    }
};

Answer 1

You currently have:

function countBs(string) {
var result = 1;
var string = prompt("Please Enter a String");
for (count = 0; count < string.length; string++) {
    if (string.charAt(count) == "B") {
            result += 1;
            return result;
        }
    }
}

which should be:

function countBs(string) {
    var result = 0;
    var string = prompt("Please Enter a String");
    for (count = 0; count < string.length; count++) {
        if (string.charAt(count) == "B") {
            result += 1;
        }
    }
    return result;
}

(notice the count++, the change from 0->1 for result, and the moved return)

Answer 2

I think you want this:

function countBs(string) {
    var result = 0;
    var string = string || prompt("Please Enter a String");
    for (var count = 0; count < string.length; ++count)
        if (string.charAt(count) == "B")
            result += 1;
    return result;
};

Make sure it's "var count" and not just "count" or you will pollute the global sapce.

There are other ways as well:

"BBBBBB".split('B').length-1

and

("BBBBBBB".match(/B/g)||"").length

or case insensitive

("BbBbBbB".match(/B/gi)||"").length

Answer 3

function countBs() {                                      // no parameter
    var string = prompt("Please Enter a String");         // provide string
    return string.split('').reduce(function (x, letter) { // string became array and array can use build in method reduce
        return letter === 'B' ? x + 1 : x;                // test for B and return increment, otherwise old count
    }, 0);                                                // start with count 0
};

take the string and make a real array, and then iterate over all letters and count the Bs

Answer 4

You need to change string in the for loop to count

function countBs(string) {
    var result = 1;
    var string = prompt("Please Enter a String");
    for (count = 0; count < string.length; count++) {
        if (string.charAt(count) == "B") {
            result += 1;

        }
    }
 return result;
};