Struggling with nested array iteration in JavaScript-based node

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1

I’m working on a project using a JavaScript-based node to process data from an API. The API returns a large JSON object with nested arrays. I can handle single-level arrays fine, but now I’m having trouble with more deeply nested ones.

Below is a sample of my input data:

{
  "success": true,
  "articles": [
    {
      "id": "xyz789",
      "headline": "Breaking news story",
      "brief": "Quick summary of the news.",
      "category": "public",
      "datePosted": "2023-03-15T12:30:00.000Z",
      "url": "https://example.com/news/xyz789",
      "topics": [],
      "keywords": ["news", "breaking", "story"],
      "metadata": [
        {
          "kind": "source",
          "total": 2,
          "items": ["Reporter A", "Reporter B"],
          "origin": "verified"
        }
      ]
    }
  ]
}

My current code processes it like this:

const output = []
for (const entry of data) {
  output.push(...entry.json.articles)
}

return output.map(item => {
  const result = {};
  for (const prop in item) {
    if (prop === 'keywords') {
      result[prop] = item[prop].join('\n');
    } else if (prop === 'metadata') {
      result[prop] = item[prop].map(info => info.kind).join('\n');
    } else {
      result[prop] = typeof item[prop] === 'object' ? JSON.stringify(item[prop]) : item[prop];
    }
  }
  return { result };
})

The issue I’m facing is that the ‘metadata’ field outputs an empty value. How can I properly handle these nested arrays to make sure all data is displayed correctly? I’m not too experienced with JavaScript, so any suggestions are really appreciated!

2

I see you’re grappling with nested array iteration. Your approach is on the right track, but you’re not fully accessing the nested data in the ‘metadata’ field. Here’s a suggestion to modify your code:

For the ‘metadata’ property, try this:

result[prop] = item[prop].map(info => {
return ${info.kind}: ${info.total}, Items: ${info.items.join(', ')}, Origin: ${info.origin};
}).join(‘\n’);

This will extract all the relevant information from each metadata object, including the ‘kind’, ‘total’, ‘items’, and ‘origin’. It should resolve your issue with empty metadata output.

Remember to handle potential undefined values or empty arrays to avoid errors. Also, consider using more descriptive variable names for better code readability.

3

As someone who’s dealt with similar issues, I can tell you that nested arrays can be tricky. Your approach is close, but you’re not digging deep enough into the metadata structure. Here’s what I’d suggest:

For the metadata field, try this:

result[prop] = item[prop].map(info => {
const itemsStr = info.items ? info.items.join(‘, ‘) : ‘N/A’;
return ${info.kind} (${info.total}): ${itemsStr} [${info.origin}];
}).join(’\n’);

This will give you a more comprehensive output for each metadata object. It handles potential missing data and provides a clear format.

Also, consider using Object.entries() instead of for…in to iterate over object properties. It’s generally safer and more predictable. Like this:

Object.entries(item).forEach(([prop, value]) => {
// Your logic here
});

Hope this helps you get unstuck!

4

hey sophialee92, looks like ur having trouble with those nested arrays. for the metadata field, try something like this:

result[prop] = item[prop].map(info => ${info.kind}: ${info.items.join(', ')}).join(‘\n’);

this should give u a string with each metadata item’s kind and items. hope it helps! lemme know if u need more help