Binding Direction Arrow Keys Up, Down, Left and Right in Javascript

binding direction arrow keys.js

document.onkeydown = function(e) {
    switch(e.which) {
        case 37:
        // left direction
        break;

        case 38:
        // up direction
        break;

        case 39:
        // right direction
        break;

        case 40:
        // down direction
        break;

        default: return; // exit this handler for other keys
    }

    e.preventDefault(); // prevent the default action (scroll / move caret)
};