What is the best way to determine if an array of objects is empty?

Question

What is the best way to determine if an array of objects is empty?

I am trying to determine whether the array of objects is empty after receiving data from an API call and storing it in the state variable city_name.

cities = this.state.city_name;
console.warn(cities); //this returns an empty array []
cities === null ? console.log(cities) : ToastAndroid.showWithGravity('No Result Found',ToastAndroid.LONG)

However, I keep encountering the error

double java.lang.Double.doubleValue() on a null object

. I have also attempted using cities.length == 0 and

(this.state.city_name).length == 0

, but they result in the same error.

Below is the data received from the API call:

city_name = [{"country_flag_url": "https://b.zmtcdn.com/images/countries/flags/country_216.png", "country_id": 216, "country_name": "United States", "discovery_enabled": 1, "has_go_out_tab": 0, "has_new_ad_format": 0, "id": 11282, "is_state": 0, "name": "Del Aire, CA", "should_experiment_with": 0, "state_code": "CA", "state_id": 73, "state_name": "California"}, {"country_flag_url": "https://b.zmtcdn.com/images/countries/flags/country_216.png", "country_id": 216, "country_name": "United States", "discovery_enabled": 0, "has_go_out_tab": 0, "has_new_ad_format": 0, "id": 4463, "is_state": 0, "name": "Del Norte, CO", "should_experiment_with": 0, "state_code": "CO", "state_id": 74, "state_name": "Colorado"}, {"country_flag_url": "https://b.zmtcdn.com/images/countries/flags/country_216.png", "country_id": 216, "country_name": "United States", "discovery_enabled": 0, "has_go_out_tab": 0, "has_new_ad_format": 0, "id": 9431, "is_state": 0, "name": "Del Rio, TX", "should_experiment_with": 0, "state_code": "TX", "state_id": 111, "state_name": "Texas"}]

I would appreciate any assistance with resolving this issue. Thank you.

javascript arrays react-native

Answer 1

Answer №1

Here is an example of how to achieve this:

 let cities = this.state.city_name;
 
 let numOfCities = cities.length;
 
 if(numOfCities == 0) {
     console.log('No city found')
       }
 
 else {
     console.log(cities)
       }

Answer 2

Here is an example of how to achieve this:

 let cities = this.state.city_name;
 
 let numOfCities = cities.length;
 
 if(numOfCities == 0) {
     console.log('No city found')
       }
 
 else {
     console.log(cities)
       }

Answer 3

Answer №2

First, make sure to check the size of the array before proceeding with your task.

if(cities.length)
// Complete your task in this section
else
// Manage the situation here

Answer 4

First, make sure to check the size of the array before proceeding with your task.

if(cities.length)
// Complete your task in this section
else
// Manage the situation here

Answer 5

Answer №3

It seems like the problem could be stemming from your use of ===, which is a strict comparison operator that might cause an error when dealing with different data types. When comparing null (a string) to a double (a number), it can lead to unexpected results.

if(cities != null && cities.length > 0){
    //perform actions on non-empty data
}else{
    //handle case where array is empty
}

Answer 6

It seems like the problem could be stemming from your use of ===, which is a strict comparison operator that might cause an error when dealing with different data types. When comparing null (a string) to a double (a number), it can lead to unexpected results.

if(cities != null && cities.length > 0){
    //perform actions on non-empty data
}else{
    //handle case where array is empty
}

What is the best way to determine if an array of objects is empty?

Answer №1

Answer №2

Answer №3

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