CODEWITHSUNDEEP
javascriptarrays
user3250966
user3250966

Reputation: 139

How to count the number of arrays nested within a JavaScript object by name

I have a generic function that needs to check the number of items in the array that is named, but I don't always know what the name is going to be called. Is there a way to do this?

array:

// added array example here per request:
var myArray = { "name": "myname", "data": [ "item1": [1], "item2": [2,3,4,5,6,7,8,9], "item3": [41,42,51,491]}

// where length is the number of objects in the array.
var mycount = someitem.getProperty("UnknownName").length;

what I want to do is call some function that does this:

var mycount = specialCountFunction(someitem, name);

Upvotes: 0

Views: 107

Answers (2)

Faiz Shukri
Faiz Shukri

Reputation: 95

Do you mean to get the length of an array in an object?

For example, your object

var obj = {
    "children": [ "john", "mark", "sam" ]
}

Get the length with obj["children"].length

Or the length of an object ?

Object.size = function(obj) {
    var size = 0, key;
    for (key in obj) {
        if (obj.hasOwnProperty(key)) size++;
    }
    return size;
};

// Get the size of an object
var size = Object.size(obj);

Upvotes: 1

cookie monster
cookie monster

Reputation: 10972

In your specialCountFunction(), receive the property name as a string, and then use square brackets after item to evaluate the value of the string in order to use it as a property name.

function specialCountFunction(item, name) {
    return item[name].length;
}

So then you'd call it like this:

var name = "whatever_the_name_is";
var count = specialCountFunction(someitem, name);

Upvotes: 1

Related Questions