JSFiddle - React, Tailwind, and code Playground

HTML

<body>
<input type="button" id="open" value="Open Compose" />
<input type="button" id="init" value="Init Streak" />
</body>

JavaScript

var Gmail = {
    openCompose: function() {
        alert('opening a compose window');
    }
}

var Streak = {
    addButtons: function() {
        alert('adding Streaks buttons');
    },
    init: function() {
        Gmail.originalOpenCompose = Gmail.openCompose;
        Gmail.openCompose = function() {
            Gmail.originalOpenCompose();
            Streak.addButtons();
        }
        //I just don't want you clicking this twice.
        $("#init").hide();
    }
}

$("#open").click(function() {
    Gmail.openCompose();
});
$("#init").click(function() {
    Streak.init();
});