Insert object into specific position in an array based off property match

Question

I've been at this for a few days and sadly I'm just not able to find the right search terms or the right answers to my lack of skill.

I'm converting ListServ to Discourse. I'm converting the RSS feeds to JSON. example of the source data:

  {
    "title": "tech: 18F presentation",
    "id": 2,
    "body": "Sadly, my biggest concern is whether it will run on Linux or Windows. And I guess if they’ll thrown even more java at it.",
    "date": "Fri, 28 May 2021 20:50:04 +0000",
    "author": "john_doe"
  },
  {
    "title": "Re: tech: 18F presentation",
    "id": 3,
    "body": "throw more java, indeed. What a moon shot.",
    "date": "Fri, 28 May 2021 20:50:04 +0000",
    "author": "john_doe2"
  },
  {
    "title": "Re: tech: 18F presentation",
    "id": 4,
    "body": "Please stop saying moonshot, its not dodgecoin",
    "date": "Fri, 28 May 2021 20:50:04 +0000",
    "author": "jane_doe"
  },

My data structure needs to look like this:

{
   "topics": [
      {
        "id": 1,
        "title": "tech: 18F presentation",
        "pinned": false,
        "posts": [
    {
     "title": "Re: tech: 18F presentation",
     "id": 3,
     "body": "throw more java, indeed. What a moon shot.",
     "date": "Fri, 28 May 2021 20:50:04 +0000",
     "author": "john_doe2"
     },
    {
     "title": "Re: tech: 18F presentation",
     "id": 4,
     "body": "Please stop saying moonshot, its not dodgecoin",
     "date": "Fri, 28 May 2021 20:50:04 +0000",
     "author": "john_doe2"
     },
        ]
      }
    ]
  }

I need each title with "Re: " to be inserted into the original title. Example) any reply, "Re tech: 18F presentation" needs to be inserted into posts: [] of the title: "tech: 18F presentation" (no Re: ).

I've tried to sperate the replies into its own json and push that into the post array, but I'm not able to figure out how to match the appropriate title.

    let data = [];
  const original_post = [];
  const reply_to_post = [];
  const discourse_JSON = [];
    $("item").map(function (i, article) {
        const title = $(article).find("title")[0].children[0].data;
    const description = $(article).find("description")[0].children[0].data;
    const user_email = $(article).find("author")[0].children[0].data.match("<([^>]+)>")[1];
    const link = $(article).find("link")[0].children[0].data;
    const guid = $(article).find("guid")[0].children[0].data;
    const date = $(article).find("pubDate")[0].children[0].data;
    const name = user_email.substring(0,user_email.indexOf('@')).split("_")[0] + ' ' + user_email.substring(0,user_email.indexOf('@')).split("_")[1];
    const username = user_email.substring(0,user_email.indexOf('@'))
        if (
            !title.toLowerCase().includes("vacancy") &&
            !title.toLowerCase().includes("opportunity") &&
            !title.toLowerCase().includes("retirement") &&
      !title.toLowerCase().includes("position") &&
      !title.toLowerCase().includes("job posting") && 
      !description.toLowerCase().includes("vacancy announcement")  &&
      !description.toLowerCase().includes("vacancy posting") &&
      !description.toLowerCase().includes("vacancies")

        ) {
 

   data.push({
    "title": title,
    "id": i,
    "body": description,
    "date": date,
    "author": username







    }
});

Answer 1

This is really just a 'groupBy' with a some string manipulation to determine hierarchy.

Here is an example using Array#reduce() and checking if the title startsWith() 'Re:'. If so, remove the initial 'Re:' using String#replace() and trim() any white space for consistency.

const
  input = [{ "title": "Re: Re: Re: tech: 18F presentation", "id": 3, "body": "throw more java, indeed. What a moon shot.", "date": "Fri, 28 May 2021 20:50:04 +0000", "author": "john_doe2" }, { "title": "tech: 18F presentation", "id": 2, "body": "Sadly, my biggest concern is whether it will run on Linux or Windows. And I guess if they’ll thrown even more java at it.", "date": "Fri, 28 May 2021 20:50:04 +0000", "author": "john_doe" }, { "title": "Re: tech: 18F presentation", "id": 4, "body": "Please stop saying moonshot, its not dodgecoin", "date": "Fri, 28 May 2021 20:50:04 +0000", "author": "jane_doe" }, { "title": "Re: other: Title", "id": 6, "body": "throw more java, indeed. What a moon shot.", "date": "Fri, 28 May 2021 20:50:04 +0000", "author": "john_doe2" }, { "title": "other: Title", "id": 5, "body": "Sadly, my biggest concern is whether it will run on Linux or Windows. And I guess if they’ll thrown even more java at it.", "date": "Fri, 28 May 2021 20:50:04 +0000", "author": "john_doe" },],

  byTopic = input.reduce((acc, { title, ...post }) => {
    if (title.startsWith('Re:')) {
      const topic = title.replace(/^(?:Re: ){1,}/, '').trim();
      acc[topic] || (acc[topic] = { posts: [] });
      acc[topic].posts.push({ title: topic, ...post });
      // using nullish coalescing assignment
      // (acc[topic] ??= { posts: [] }).posts.push({ title: topic, ...post });
    } else {
      acc[title] = {
        id: post.id, // your example changes id in the expected output, unsure of the logic
        title: title,
        pinned: false, // not sure where pinned is coming from
        posts: acc[title] ? acc[title].posts : []
        // using optional chaining and nullish coalescing
        // posts: acc[title]?.posts ?? []
      }
    }
    return acc;
  }, {})

console.log(Object.values(byTopic));

.as-console-wrapper { max-height: 100% !important; top: 0; }

As I mentioned in the comments, using reduce() in this way can be directly replaced with an external accumulator and a for loop. Here using a for...of

const input = [{ "title": "Re: Re: Re: tech: 18F presentation", "id": 3, "body": "throw more java, indeed. What a moon shot.", "date": "Fri, 28 May 2021 20:50:04 +0000", "author": "john_doe2" }, { "title": "tech: 18F presentation", "id": 2, "body": "Sadly, my biggest concern is whether it will run on Linux or Windows. And I guess if they’ll thrown even more java at it.", "date": "Fri, 28 May 2021 20:50:04 +0000", "author": "john_doe" }, { "title": "Re: tech: 18F presentation", "id": 4, "body": "Please stop saying moonshot, its not dodgecoin", "date": "Fri, 28 May 2021 20:50:04 +0000", "author": "jane_doe" }, { "title": "Re: other: Title", "id": 6, "body": "throw more java, indeed. What a moon shot.", "date": "Fri, 28 May 2021 20:50:04 +0000", "author": "john_doe2" }, { "title": "other: Title", "id": 5, "body": "Sadly, my biggest concern is whether it will run on Linux or Windows. And I guess if they’ll thrown even more java at it.", "date": "Fri, 28 May 2021 20:50:04 +0000", "author": "john_doe" },];

const byTopic = {};

for (const { title, ...post } of input) {
  if (title.startsWith('Re:')) {
    const topic = title.replace(/^(?:Re: ){1,}/, '').trim();
    byTopic[topic] || (byTopic[topic] = { title: topic, posts: [] });
    byTopic[topic].posts.push({ title: topic, ...post });
  } else {
    byTopic[title] = {
      id: post.id,
      title: title,
      pinned: false,
      posts: [],
      ...byTopic[title]
    }
  }
};

console.log(Object.values(byTopic));

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

Here is a simple solution using the Array.forEach operator. There are probably more efficient solutions, which may be important if you have a large data set:

const source = [{title:"tech: 18F presentation",id:2,body:"Sadly, my biggest concern is whether it will run on Linux or Windows. And I guess if they’ll thrown even more java at it.",date:"Fri, 28 May 2021 20:50:04 +0000",author:"john_doe"},{title:"Re: tech: 18F presentation",id:3,body:"throw more java, indeed. What a moon shot.",date:"Fri, 28 May 2021 20:50:04 +0000",author:"john_doe2"},{title:"Re: tech: 18F presentation",id:4,body:"Please stop saying moonshot, its not dodgecoin",date:"Fri, 28 May 2021 20:50:04 +0000",author:"jane_doe"}];

let = formatted = [];
// Loop over the original data, find parents
source.forEach((item) => {
  // Is not a reply
  if (item.title.indexOf('Re:') === -1) {
    formatted.push(item);
  }
});
// Find children, append to parents
source.forEach((item) => {
  formatted.forEach((parent) => {
    // Child contains parent title.
    if (item.title.indexOf(parent.title) !== -1 && item.title.indexOf('Re:') !== -1) {
      if (!parent.data) {
        parent.data = [];
      }
      parent.data.push(item);
    }
  })
});
console.log(formatted);