// This code will automatically save the current canvas as a .png file. 
// Its useful as it can be placed in a loop to grab multiple canvas frames, I use it to create thumbnail gifs for my blog
// Only seems to work with Chrome

// Get the canvas
var canvas = document.getElementById("canvas");
// Convert the canvas to data
var image = canvas.toDataURL();
// Create a link
var aDownloadLink = document.createElement('a');
// Add the name of the file to the link
aDownloadLink.download = 'canvas_image.png';
// Attach the data to the link
aDownloadLink.href = image;
// Get the code to click the download link
aDownloadLink.click();