Repository

https://github.com/igormuba/steemhere/tree/class5
I am making new branches according to the class

What Will I Learn?

We have already learned how to make a post to the blockchain, now we will learn

steem.js library: Retrieve the last post by user
steemconnect JavaScript library Make a comment on a post
DOM manipulation (AKA magic): Only show the comment field after posting

Requirements

It is recommended that you have followed the last tutorials to understand what are we doing (links on the bottom of the page), sels you need

Basic JSON knowledge
Basic HTML knowledge
Intermediate JavaScript knowledge
Steem account
SteemConnect app

Difficulty

Intermediate

Tutorial Contents

My motivation for this series:

I have started this series because of my frustration with the lack of tutorials and learning materials to work with the Steem and SteemConnect API. The documentation they have is NOT beginner friendly and very intimidating. My goal is to make things as simple and beginner friendly as possible, and even copy and paste friendly if possible.
I hope someday a better developer than me see this tutorials and take his time to make his own and better tutorials (or if lacks time contact me and help in this series), or even Steem/SteemConnect team realize their API documentation and tutorials are not very beginner friendly

Previously

We will follow up with the SteemConnect API, previously we have tweaked the comment function to make a post, but now we will also start using the Steem JavaScript library to add more functionality and flexibility. The SteemConnect API is useful for posting and doing things that require your authorization, but when you just need to retrieve posts or data that are publicly available you can use the Steem JS library itself since it does not require authentication.

New JavaScript file

I am creating a new file called myscript5.js inside the JS folder of the project of this classes, we could make everything on the old JavaScript file but after I finished the testings for this class I have realized that the code was too big, so I have started again putting all the new content on this new file and trying to make it cleaner than the old one, which still has the functions of the old tutorials

Importing Steem JS library and the new JS file

<script src="js/myscript5.js"></script> 


<script src="https://cdn.steemjs.com/lib/latest/steem.min.js"></script>

You can read more about on their github
https://github.com/steemit/steem-js/tree/master/doc

Getting the last post by author

This is the function to get the last posts by the author
steem.api.getDiscussionsByAuthorBeforeDate(author, permlink, date, max, function(err, result){}

I will add it into the old myscript.js file so we can use the variables we have already used to make things simple, I want you to understand the function itself, not lose time starting again what we have already done.

So, previously we have put on the myscript.js file the function from the SteemConnect API
api.comment("", parentPermlink, author, permlink, title, body, jsonMetadata, function (err, res) to make a post, not a comment, right below that we will use the other API, the Steem API.

So do as following:

  steem.api.getDiscussionsByAuthorBeforeDate(author, permlink, '2019-05-01T00:00:00', 1, function(err, result) {
  document.getElementById("retrievedPost").innerHTML = result["0"].body;
  document.getElementById("retrievedTitle").innerHTML = result["0"].root_title;

  document.getElementById("commentElement").innerHTML = `
    Content 

    
  `;

  });

Did you notice a few things?
document.getElementById("retrievedPost")
and
document.getElementById("retrievedTitle")

They are there so we can change an HTML element to the text we retrieved from the blockchain.
So, let us jump into the index.html file and add them there before I explain the rest

You simply need to add

  <h1 id="retrievedTitle">title</h1>
    <p id="retrievedPost">post</p>

Now, back to the JavaScript, I will show you the structure of the JSON element we have received and is stored in the object result

But the only things we want here are the body and the title. I will show you how to get it and depending on your application you can use the same pattern to get other elements!
result["0"].InsertHereWhatYouWant;
In our case we want the body and the title, this is why we have put on the code above .body and .title

If you want to see all the elements of the json, put inside the function a console.log, on the example below I am hard coding my username and no permlink to get the very very last post just to show you what to do to see the data structre of the JSON, this will print the last post on the console

steem.api.getDiscussionsByAuthorBeforeDate("igormuba", "", '2019-05-01T00:00:00', 1, function(err, result){
console.log(result);
});

DOM manipulation to hide/show elements

Moving on, the next thing from the screenshot/chunk of code I want to explain is

Here we are using JavaScript to make a very fancy DOM manipulation, it looks like we are coding HTML inside the JavaScript file, right?

What this does is:
After we have retrieved the last post, only then we will show the "post comment field", this is fancy (though my presentation is ugly) but it is important to keep in mind we can do this to remove from the page unnecessary content, I thought it would be a neat trick to show you. You can do this for many chunks of code but here we are keeping things simple.

Submiting the comment

Now that we have added the code to retrieve the last post, understood it and displayed the make comment HTML content to the user is time to make our own comment, the final code will look like

But as Mr. Hannibal would say, "let us separate it into parts"

First we are declaring a function called submitComment(), inside it:

First, we are giving a title to the comment by just adding "re ", to mean reply, to the comment, most interfaces won't even show this

var commentTitle = title=document.getElementById("title").value;
  commentTitle = "re "+commentTitle;

Now, we are getting the comment content from the HTML chunk of code we have magically put inside a JavaScript, that one that only shows after we have posted and retrieved the post

var commentContent = document.getElementById("commentContent").value;

Now, we are flexing our JavaScript muscles to get the the title from the HTML, that we have filled 1 class ago, to turn it into the parent permLink

var parentPermlink= document.getElementById("retrievedTitle").innerHTML;
  parentPermlink = parentPermlink.replace(/ /g, "-");
  parentPermlink = parentPermlink.toLowerCase();

The author we also get from the HTML that we have filled 2 classes back

var author=document.getElementById("username").innerHTML;

We are also using the parent permLink to generate the answer permlink by just adding "re-" before the parent link

var permLink = "re-"+parentPermlink;

Now we just use the comment function we have used in the other tutorial to make a post, but previously we have tweaked it to make full posts, now we are filling the parameters to make a real comment inside a real post

api.comment(author, parentPermlink, author, permLink, "", commentContent, "", function (err, res)

So, now, if you jump into the index.html you should be able to

make a post
see the post on your screen
the DOM magic will make the comment field appear
fill the field and make a comment

Curriculum

Proof of Work Done

index.html
https://github.com/igormuba/steemhere/blob/class5/index.html

myscript.js
https://github.com/igormuba/steemhere/blob/class5/js/myscript.js

myscript5.js
https://github.com/igormuba/steemhere/blob/class5/js/myscript5.js

Hey, I am Witness, did you know?

To vote for me, simple use the SteemConnect link below
https://steemconnect.com/sign/account-witness-vote?witness=igormuba&approve=1

or go to https://steemit.com/~witnesses

(note, it is /~witnesses, not /witness)
Scroll all the way down to "If you would like to vote for a witness outside of the top 100, enter the account name below to cast a vote."

type igormuba and click vote

(Part 5)Tutorial On Steem/SteemConnect JS Retrieve And Comment The Last Post @steemconnect pt5