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

4ff0d75c8ed2842c1266099b

Here is what I wrote:

Array.prototype.contains = function(k) {
  for(p in this)
     if(this[p] === k)
        return true;
  return false;
}

Apparently, it doesn't work properly, or better sometimes it works, but it looks to me blocking. Is there anyone that can check that one?

many thanks

1
15
7/2/2012 1:31:09 AM

Accepted Answer

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/

32
11/4/2012 2:40:31 PM

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