Create a chatter post from Apex class on any object and show some Toast message on VF page

We can post a chatter on any object with the help of the Apex class.

we can inject this code in my apex class and create a post


FeedItem post = new FeedItem();
                post.ParentId = objecct Id; // id of any object
                post.Body = 'This is my first post on chatter'; // body of the post
                insert post;
========================================================================
Toast message using Java script 


<apex:page lightningStylesheets="true">
    <script>
        function showToast() {
            sforce.one.showToast({
                "title": "Success!",
                "message": "Welcome to salesforce code crack.",
                "type": "success"
            });
        }
    </script>
    <apex:form >
        <apex:page >
            <apex:commandButton value="Show Toast" onclick="showToast();" />
        </apex:page>
    </apex:form>
</apex:page>