less.js/lib/less/tree.js

var tree = exports;

tree.operate = function (op, a, b) {
    switch (op) {
        case '+': return a + b;
        case '-': return a - b;
        case '*': return a * b;
        case '/': return a / b;
    }
};

tree.find = function (obj, fun) {
    for (var i = 0, r; i < obj.length; i++) {
        if (r = fun.call(obj, obj[i])) { return r }
    }
    return null;
};