Matt Kirman

How to recreate the Konami code in Javascript

Facebook has featured in social media blogs recently for adding a Konami code Easter egg to their home page. In this blog post I show you how to add similar “functionality” to your site using Javascript.

First, the full code:

// check to make sure that the browser can handle window.addEventListener
if (window.addEventListener) {
    // create the keys and konami variables
    var keys = [],
        konami = "38,38,40,40,37,39,37,39,66,65";
    // bind the keydown event to the Konami function
    window.addEventListener("keydown", function(e){
        // push the keycode to the 'keys' array
        // and check to see if the user has entered the Konami code
        if (keys.toString().indexOf(konami) >= 0) {
            // do something such as:
            // alert('Konami');
            // and finally clean up the keys array
            keys = [];
    }, true);

The script adds a callback function to the keydown event which stores the keycode in the keys array. It then checks the array against the pre-defined konami array (which contains a keycoded version of the Konami code).

Found the Konami code (or any other easter eggs) on the web? Let me know in the comments.