Iterate in a javascript subobject with an unknown name [duplicate]

Question

I'm parsong RSS news using javascript.. The object returned (from Yahoo YQL) has the news inside a news object.

Normally, it's inside this subobject:

news.results.item

So I would just iterate normally using:

news.results.item.forEach

Now it gets interesting when I'm loading multiple sources.. it can return stuff like

news.results.item (array[10])
news.results.entry (array[10])
news.results.banana (array[10])

My question is, how can I iterate inside these entries when I don't know the naming that will be returned.. is there a simple way to merge them all? (Using jQuery is fine)

T.J. Crowder · Accepted Answer · 2016-11-10 18:34:38Z

You can loop through all of the array properties on news.results:

var news = {
    results: {
        item: ["a", "b", "c"],
        entry: ["d", "e", "f"],
        banana: ["g", "h", "i"]
    }
};
Object.keys(news.results).forEach(function(key) {
    var value = news.results[key];
    if (Array.isArray(value)) {
        value.forEach(function(entry) {
            console.log(entry);
        });
    }
});

And if you're looking for something specific and want to stop when you find it, you can use some instead of forEach or do a nested find (you'll need a find polyfill for some browsers still).

But if you want to combine them before searching, that's fairly easily done:

var news = {
    results: {
        item: ["a", "b", "c"],
      entry: ["d", "e", "f"],
        banana: ["g", "h", "i"]
    }
};
var all = [];
Object.keys(news.results).forEach(function(key) {
    var value = news.results[key];
    if (Array.isArray(value)) {
        all.push.apply(all, value);
    }
});
all.forEach(function(entry) {
  console.log(entry);
});

(Some people would use reduce for that. I think it obscures rather than aiding reading in cases like this where the accumulation value never actually changes.)

guest271314 · Accepted Answer · 2016-11-10 17:50:15Z

0

You can use Object.keys(), for..of loop

let news = {
  result: {
    item: [1,2,3],
    entry: [4,5,6],
    banana: [7,8,9]
  }
}

for (let key of Object.keys(news.result)) {
  console.log(`${key}:`);
  for (let entries of news.result[key]) {
    console.log(entries)
  }
}

edited Nov 10, 2016 at 17:50

answered Nov 10, 2016 at 17:35

guest271314

1

4 Comments

guest271314 Over a year ago

@T.J.Crowder Not certain what you mean? OP is expecting possibly more than single property at result object? E.g., result could contain item, entry and banana?

guest271314 Over a year ago

@T.J.Crowder See updated post.

T.J. Crowder Over a year ago

Yes, that fixes it. Beware of browser support for Object.entries, it's an ES2017 thing.

guest271314 Over a year ago

@T.J.Crowder See updated post. Object.keys() returns expected result by adjusting pattern. Initially interpreted Question as only one property would be set at object.

Sagar · Accepted Answer · 2016-11-10 18:07:35Z

0

Updated answer as pointed out by T.J. Crowder

var news = {
  results: {
    item: ["a", "b", "c"],
    entry: ["d", "e", "f"],
    banana: ["g", "h", "i"]
  }
};

for (var key in news.results) {
  console.log(key + " " + news.results[key])

}

edited Nov 10, 2016 at 18:07

answered Nov 10, 2016 at 17:46

Sagar

5383 silver badges9 bronze badges

2 Comments

T.J. Crowder Over a year ago

There is zero need for jQuery here. It's 2016. Arrays have had forEach for several years.

sigmaxf Over a year ago

arrays do, but objects do not support forEach

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