Question

I have a javascript object and I need to reference the value of one of it’s children. The child should be part of an array.

This works:

this.manager.response.highlighting[doc.id]['sentence_0002']

But this doesn’t:

this.manager.response.highlighting[doc.id][0]

I don’t know which sentence_000* numbers are going to be returned, so I want to reference it by it’s array number.

this.manager.response.highlighting[doc.id].length

doesn’t return anything either.

Here is a portion of the xml document that was turned into the javascript object:

<response>
  <lst name="highlighting">
    <lst name="http://www.lemonde.fr/international/">
      <arr name="sentence_0005">
        <str> puni pour sa gestion de la crise Geir Haarde a été condamné pour avoir manqué aux devoirs de sa </str>

What I need to access is the value in <str>. doc.id is successfully set to http://www.lemonde.fr/international/.

Answer 1

If highlighting[doc.id] has a property with a name like sentence_xyz, there is no positional order to that property, but you can find out what keys exist using a for..in loop:

var key, val;
var obj = this.manager.response.highlighting[doc.id];
for (key in obj) {
    // Here, `key` will be a string, e.g. "sentence_xyz", and you can get its value
    // using
    val = obj[key];
}

You may find you need to filter out other properties, which you can do with the usual string methods, e.g.:

for (key in obj) {[
    if (key.substring(0, 9) === "sentence_") {
        // It's a sentence identifier
    }
}

You may also find hasOwnProperty useful, though I’m guessing this is a deserialized object graph from a JSON text response, in which case hasOwnProperty doesn’t really come into it.