href
The URL to share. If you set this attribute by using gapi.plus.render, you should should not escape the URL.
Possible values: Any URL
Default: Current page's URL

annotation
The annotation to display next to the button.
Possible values: inline, bubble, vertical-bubble, none
Default: bubble

width
The maximum width to allocate to the entire share plugin. See Button Sizes for more information.
Possible values: Any number
Default: —

height
The height to assign the button. This may be 15, 20, 24 or 60. See Button Sizes for more information.
Possible values: Any number
Default: 20

align
Sets the alignment of the button assets within its frame.
Possible values: left, right
Default: left

expandTo
The preferred positions in which to display hover and confirmation bubbles, relative to the button. Set this parameter when your page contains certain elements, such as Flash objects, that might interfere with rendering the bubbles.
If omitted, the rendering logic will guess the best position, usually defaulting to below the button (bottom).
Possible values: comma-separated list of top, right, bottom, left
Default: empty list

onstartinteraction
If specified, this function is called when an interaction bubble appears (such as when the user hovers over the button or starts the sharing flow). This function must be in the global namespace and may accept a single parameter, which will be a JSON object.
Possible values: function(jsonParam)
Default: —

onendinteraction
If specified, this function is called when the interaction bubble disappears. You can use this callback function to modify your page, such as resuming a video, when the bubble closes. This function accepts a single parameter, which is identical in structure to the parameter passed to onstartinteraction.
Possible values: function(jsonParam)
Default: —