.cs

public void OnButtonClick()
{
    Debug.Log("Button Clicked: " + name);

    // determin which button
    if (name.CompareTo("JoinButton") == 0)
    {
        // join chat
        OnJoinButtonClicked();
    }
    else if (name.CompareTo("LeaveButton") == 0)
    {
        // leave chat
        OnLeaveButtonClicked();
    }
}

private void OnJoinButtonClicked()
{
    Debug.Log("Join button clicked");

    // get channel name from text input
    GameObject go = GameObject.Find("ChannelName");
    InputField input = go.GetComponent<InputField>();
}

private void OnLeaveButtonClicked()
{
    Debug.Log("Leave button clicked");
}