How to search in an array in Node.js in a non-blocking way?

Question

I have an array which is:

[ 4ff023908ed2842c1265d9e4, 4ff0d75c8ed2842c1266099b ]

And I have to find if the following, is inside that array

Answer 1

Non-blocking search function

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));
}

Usage:

[1, 2, 3, 4, 5].contains(3, function(found) {
    if (found) {
        console.log("Found");
    } else {
        console.log("Not found");
    }
});

However, for searching the value in the array it is better to use Javascript built-in array search function, as it will be much faster (so that you probably won't need it to be non-blocking):

if ([1, 2, 3, 4, 5].indexOf(3) >= 0) {
    console.log("Found");
} else {
    console.log("Not found");
}

Also, consider the underscore library which makes all the stuff cross-platform: http://underscorejs.org/