-js: solutions for chapter #3

solutions.js

function min(x, y) {
    return x >= y ? y : x;
}

function isEven(n) {
    if (n < 0)  n = Math.abs(n); // alternative: n = n * -1
    if (n == 0) return true;
    if (n == 1) return false;
    return isEven(n - 2);
}

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

function _countChar(s, ch) {
    return s.split('').filter(function (c) {
        return c === ch;
    }).map(function (c) {
        return 1;
    }).reduce(function (p, n) {
        return p + n;
    }, 0)
}

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