Posting to a Chatter Feed

1var sr = JSON.parse('<%=signedRequestJson%>');
2// Reference the Chatter user's URL from Context.Links object.
3var url = sr.context.links.chatterFeedsUrl+"/news/"+sr.context.user.userId+"/feed-items";
4var body = {body : {messageSegments : [{type: "Text", text: "Some Chatter Post"}]}};
5
6Sfdc.canvas.client.ajax(url,
7    {client : sr.client,
8        method: 'POST',
9        contentType: "application/json",
10        data: JSON.stringify(body),
11        success : function(data) {
12        if (201 === data.status) {
13             alert("Success");
14             }
15        }
16    });