array contains functionality for node js

array_contains.js

Array.prototype.contains = function(k, callback) {  
    var self = this;
    return (function check(i) {
        if (i >= self.length) {
            return callback(false);
        }
        if (self[i] === k) {
            return callback(true);
        }
        return process.nextTick(check.bind(null, i+1));
    }(0));
};