Question

So let’s assume I have a JSON file as such:

{ "store": {
"book": [ 
  { "category": "reference",
    "author": "Nigel Rees",
    "title": "Sayings of the Century",
    "price": 8.95
  },
  { "category": "fiction",
    "author": "Evelyn Waugh",
    "title": "Sword of Honour",
    "price": 12.99
  },
  { "category": "fiction",
    "author": "Herman Melville",
    "title": "Moby Dick",
    "isbn": "0-553-21311-3",
    "price": 8.99
  },
  { "category": "fiction",
    "author": "J. R. R. Tolkien",
    "title": "The Lord of the Rings",
    "isbn": "0-395-19395-8",
    "price": 22.99
  }
    ]
  }
}

What I want to do is grab a member of “book” and all of its string value pairs where title is “Sword of Honour”. How can I do that with JQuery? The problem is that I don’t know the index ID of the the member, if I did it would be trivial, i.e. store.book[1].XXX would give me the value of all of the sibling key value pairs I am looking for.

Any ideas on how I can do this with minimum code?

Answer 1

Using array filter:

var matches = store.book.filter(function(val, index, array) {
    return val.title === 'Sword of Honour';
});

The result will be an array of all of the book elements that match the filter predicate.

NB: this is an ES5 method. There’s a shim on the linked MDN page for non-ES5 browsers.