example.js

Polymer.fc = {
    properties: {
        _elevation: {
            type: Number
        }
    },
    observers: ["_calculateElevation(focused, disabled, active, pressed, receivedFocusFromKeyboard)"],
    hostAttributes: {
        role: "button",
        tabindex: "0"
    },
    nc: function() {
        var a = 1;
        this.disabled ? a = 0 : this.active || this.pressed ? a = 4 : this.receivedFocusFromKeyboard && (a = 3);
        this._elevation = a
    }
};