如何在AngularJS中获取值为x的项目的行数？

Question

I have the following object

    var countries = [
        {country: "Ireland", continent: "Europe", language: "English"},
        {country: "Spain", continent: "Europe", language: "Spanish"},
        {country: "United Kingdom", continent: "Europe", language: "English"},
        {country: "France", continent: "Europe", language: "French"},
        {country: "Germany", continent: "Europe", language: "(other)"},
        {country: "Sweden", continent: "Europe", language: "(other)"},
        {country: "Norway", continent: "Europe", language: "(other)"},
        {country: "Italy", continent: "Europe", language: "(other)"},
        {country: "Greece", continent: "Europe", language: "(other)"},
        {country: "Iceland", continent: "Europe", language: "(other)"},
        {country: "Portugal", continent: "Europe", language: "Portuguese"},
        {country: "Malta", continent: "Europe", language: "(other)"},
        {country: "Brazil", continent: "South America", language: "Portuguese"},
        {country: "Argentina", continent: "South America", language: "Spanish"},
        {country: "Colombia", continent: "South America", language: "Spanish"},
        {country: "Peru", continent: "South America", language: "Spanish"},
        {country: "Venezuela", continent: "South America", language: "Spanish"},
        {country: "Uruguay", continent: "South America", language: "Spanish"}
    ];

How can I count the objects with for example continent === 'South America' ? It is a JSON list of obejcts returned from a WebService within an AngularJS Controller.

Answer 1

You can use Array#reduce()

 var countries = [{"country":"Ireland","continent":"Europe","language":"English"},{"country":"Spain","continent":"Europe","language":"Spanish"},{"country":"United Kingdom","continent":"Europe","language":"English"},{"country":"France","continent":"Europe","language":"French"},{"country":"Germany","continent":"Europe","language":"(other)"},{"country":"Sweden","continent":"Europe","language":"(other)"},{"country":"Norway","continent":"Europe","language":"(other)"},{"country":"Italy","continent":"Europe","language":"(other)"},{"country":"Greece","continent":"Europe","language":"(other)"},{"country":"Iceland","continent":"Europe","language":"(other)"},{"country":"Portugal","continent":"Europe","language":"Portuguese"},{"country":"Malta","continent":"Europe","language":"(other)"},{"country":"Brazil","continent":"South America","language":"Portuguese"},{"country":"Argentina","continent":"South America","language":"Spanish"},{"country":"Colombia","continent":"South America","language":"Spanish"},{"country":"Peru","continent":"South America","language":"Spanish"},{"country":"Venezuela","continent":"South America","language":"Spanish"},{"country":"Uruguay","continent":"South America","language":"Spanish"}] var result = countries.reduce(function(r, e) { if(e.continent === 'South America') r++ return r; }, 0); console.log(result) 

Answer 2

You can create an array, like :

var southAfrikaResult = []

Then you loop on your countries array (with angular.forEach) and check if

item.continent === 'South Afika'

If so, then push item into your southAfricaResult. Your final result will be :

var your_result = southAfricaResult.length;

Edit : the filter solution proposed by Jose Hermosilla Rodrigo it way better.

Answer 3

I would do sth like

var countries = [
    {country: "Ireland", continent: "Europe", language: "English"},
    {country: "Spain", continent: "Europe", language: "Spanish"},
    {country: "United Kingdom", continent: "Europe", language: "English"},
    {country: "France", continent: "Europe", language: "French"},
    {country: "Germany", continent: "Europe", language: "(other)"},
    {country: "Sweden", continent: "Europe", language: "(other)"},
    {country: "Norway", continent: "Europe", language: "(other)"},
    {country: "Italy", continent: "Europe", language: "(other)"},
    {country: "Greece", continent: "Europe", language: "(other)"},
    {country: "Iceland", continent: "Europe", language: "(other)"},
    {country: "Portugal", continent: "Europe", language: "Portuguese"},
    {country: "Malta", continent: "Europe", language: "(other)"},
    {country: "Brazil", continent: "South America", language: "Portuguese"},
    {country: "Argentina", continent: "South America", language: "Spanish"},
    {country: "Colombia", continent: "South America", language: "Spanish"},
    {country: "Peru", continent: "South America", language: "Spanish"},
    {country: "Venezuela", continent: "South America", language: "Spanish"},
    {country: "Uruguay", continent: "South America", language: "Spanish"}
];

j = 0;
newCountry = [];    

for(i=0; i<countries.length; i++)
{
    if(countries[i]['continent'] == 'South America')
    { 
        j++; //only for size
        newCountry.push(countries[i]);
    }
}

Thanks that you have only number of countries but in newCountry you will have array with countries in that continent and then you can use newCountry.length and you will get same result.

Answer 4

you can create array like this

var result = [];

You angular.foreach loop

angular.forEach(countries, function(value, key) {
if(value.continent == "South America")
       //your logic
  result.push(value.continent);
});

finally you count the array length

var count = result.length;

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