Counting occurrences of Javascript array indexes

Question

I have the following array.

       "APP-A": {
            "active": true
        },
        "APP-B": {
            "active": true
        },
        "APP-C": {
            "active": true
        },
        "BOOL-A": {
            "active": true
        },
        "BOOL-B": {
            "active": true
        },
        "BOOL-C": {
            "active": true
        },

I need to get the total count of the APP-*'s in the array. Am trying to implement in angular JS. Solutions in plain JS will also be helpful.

TIA

Answer 1

One approach is to use .filter() on the object's keys:

var count = Object.keys(obj).filter(function (key) {
    return key.indexOf(prefix) === 0;
}).length;

http://jsfiddle.net/4m692usx/1/

Answer 2

may be try like this:

var items = { "APP-A": {
        "active": true
    },
    "APP-B": {
        "active": true
    },
    "APP-C": {
        "active": true
    },
    "BOOL-A": {
        "active": true
    },
    "BOOL-B": {
        "active": true
    },
    "BOOL-C": {
        "active": true
    }
};
var c=0;
for(var item in items)
{
if(item.indexOf("APP-") >= 0)      
c++;
}
console.log(c);// your count here.

Answer 3

Check this JSFiddle Link

But actually it's not an array, it's a JSON object . And what we are counting is JSON key's.

JS Part:

var items = { "APP-A": {
            "active": true
        },
        "APP-B": {
            "active": true
        },
        "APP-C": {
            "active": true
        },
        "BOOL-A": {
            "active": true
        },
        "BOOL-B": {
            "active": true
        },
        "BOOL-C": {
            "active": true
        }
};

var app_count = 0;
for(var ik in items) {
    if(ik.indexOf("APP-") >= 0) {
        app_count++;
    }
}
alert(app_count);
console.log(app_count);

Answer 4

 var myArray = { "APP-A": { "active": true }, "APP-B": { "active": true }, "APP-C": { "active": true }, "BOOL-A": { "active": true }, "BOOL-B": { "active": true }, "BOOL-C": { "active": true } }; var reg = /^APP-/, count = 0, name; for (name in myArray) { count += reg.test(name); } document.getElementById('output').innerHTML = count; 

 <div id="output"></div> 

Answer 5

That looks like a json, not an array.

var count = 0;
for (var key in json) {
    key.indexOf('APP-')!==-1?count++,count;
}

Answer 6

You can do something like this.

http://jsfiddle.net/098o3kch/1/

var items = { "APP-A": {
            "active": true
        },
        "APP-B": {
            "active": true
        },
        "APP-C": {
            "active": true
        },
        "BOOL-A": {
            "active": true
        },
        "BOOL-B": {
            "active": true
        },
        "BOOL-C": {
            "active": true
        }
};

function getCount(obj,pattern){
var cnt = 0;
 for(var item in obj)
{
if(item.indexOf(pattern) >= 0)  
cnt++;
}
return cnt;
 }

alert(getCount(items, "APP-"));