JSON/Javascript: return which array object contains a certain property

Question

Given a JSON object such as this:

{
  "something": {
    "terms": [
      {
        "span": [
          15,
          16
        ],
        "value": ":",
        "label": "separator"
      },
      {
        "span": [
          16,
          20
        ],
        "value": "12.5",
        "label": "number"
      }
    ],
    "span": [
      15,
      20
    ],
    "weight": 0.005,
    "value": ":12.5"
  }

I would like write some javascript that would determine the index of the "term" that has a "label": "number". Ultimately I want to determine the "value" of the "term" that has a "label": "number", I know I can get that with something like this, where the index is known:

parsed = JSON.parse(result.trim());
var numberValue = parsed.terms[1].value;

My first thought is perhaps to just write a foreach loop and then return the numberValue when I arrive at an array object that has "label": "number".

Is there a more elegant and/or concise way to do this?

not sure. It is a proprietary API. Is there something wrong with it? — dtburgess
– dtburgess, Commented Aug 1, 2015 at 13:20

vp_arth · Accepted Answer · 2015-07-31 13:13:55Z

1

Use Array.prototype.filter:

var numberValue, list = parsed.something.terms.filter(function(a){
  return a.label==='number';
});
numberValue = list.length ? list[0].value : -1;

edited Jul 31, 2015 at 13:13

answered Jul 31, 2015 at 13:11

vp_arth

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3 Comments

Ruan Mendes Over a year ago

In Harmony, you can use developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

vp_arth Over a year ago

However, with find you can't to get all value elements, if need.

dtburgess Over a year ago

Thank you for this. How would I modify this code to return the array index of the "term" where the "label" = "number"?

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