Finding Value in Array

Question

I am trying to find if an object contains a certain value and then have that dictate the next steps of the operation. This is an object that is returned from Google Maps API. This is an exact example returned back from their API.

Array

[{'long_name': 'United States', 'short_name': 'US'}, {'long_name': 'California', 'short_name': 'CA'}];

Conditional/Check

if( $.inArray('US', array) == -1 ){

    alert('Your country is not supported.');

} else {
     alert('Your country is supported.');   
}

This doesn't work because it only looks at the index, and not values I believe. What's the cleanest and fastest way to find and return if the value exists in the array?

@JoshuaByer: Please don't call an object "hash array", it just adds to the confusion. JS has objects and arrays are a special kind of object. — Felix Kling
– Felix Kling, Commented Apr 17, 2015 at 0:33
@Interrobang well, they don't "have to be", strictly speaking it's a syntactically valid expression. I wouldn't say "invalid" to not confuse anyone (since that's not true) — zerkms
– zerkms, Commented Apr 17, 2015 at 0:40

Ja͢ck · Accepted Answer · 2015-04-17 02:00:58Z

5

To find a match you could use jQuery.grep():

var res = $.grep(arr, function(item) {
    return item.short_name == 'US';
});

It returns an array, which will be empty if there are no matches found.

Alternatively, you could use Array.prototype.filter():

var res = arr.filter(function(item) {
    return item.short_name == 'US';
});

Bonus

You can generalise it further:

function searchFunction(field)
{
    return function(arr, term) {
        return arr.filter(function(item) {
            return item[field] == term;
        };
    };
}

var searchByShortName = searchFunction('short_name');

if (searchByShortName(arr, 'US').length) {
    // ..
}

edited Apr 17, 2015 at 2:00

answered Apr 17, 2015 at 0:32

Ja͢ck

174k39 gold badges269 silver badges317 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Miura-shi Over a year ago

Very elegant. I appreciate your time on this very educational answer. I was a little unclear in my question and I do apologize. Thank you very much!

3coins · Accepted Answer · 2015-04-17 00:47:20Z

1

What you need is something like this

var countries = [{'long_name': 'United States', 'short_name': 'US'},
{ 'long_name': 'California', 'short_name': 'CA'}]; //now this is an array with objects

function hasCountry(shortName){
    for(var i = 0, len = countries.length; i < len; i++){
        if(countries[i]['short_name'] === shortName) return true;
    }
    return false;
}

if(hasCountry('US')){
   // not supported..
} else {
   // not supported
}

However, a better solution would be normalize the countries to an object like this.

var countries = {'US': 'United States', 'CA': 'California'}; // this is an object

if(countries['US'] != null){
    // supported
} else {
  // not supported
}

edited Apr 17, 2015 at 0:47

answered Apr 17, 2015 at 0:39

3coins

1,3423 gold badges11 silver badges30 bronze badges

1 Comment

zerkms Over a year ago

1. syntax error (see syntax highlights) 2. It would be much better if hasCountry accepted both an array and a search term.

Collectives™ on Stack Overflow

Finding Value in Array

2 Answers 2

Bonus

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Bonus

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related