How can I save a javascript variable to a sequel database?

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In my javascript code I have it set up so that a canvas is saved to a javascript variable, like so:

function saveImage() {
var scanvas = document.getElementById("staff");
scanvas.getContext("2d");
var canvasData = scanvas.toDataURL("image/png");

}

}

I want to have it so that someone who wants to save that image can save it to their account on the database. Is there a way I can do that?