Nested looping around an array

Question

I am trying to loop all the values of an array and push that looped data into another array.

For example:

{
"cat": [
    {
        "view": [
            {
                "ent": [
                    {
                        "data": [
                            {}
                        ],
                        "label": "abcd"
                    },
                    {
                        "data": [
                            {}
                        ],
                        "label": "efgh"
                    }
                ]
            }
        ]
    }
]

I need to iterate until label and bring all the values of label into an array. This is what I have tried. The issue is I am just getting the last value of label i.e. won in my array variable.

JS:

var ArrL = scope.res.cat;
var Array = [];
for(var i=0;i<ArrL.length;i++){
    var ArrF = ArrL[i].view;
    for(var j=0;j<ArrF.length;j++){
        var ArrE = ArrF[j].ent;
        for(var k=0;k<ArrE.length;k++){
            var ArrLa = ArrE[k].label;

        }

    }
    Array.push(ArrLa);
}
console.log(Array);

Expected output is ['joy','won'] but output after running the program is ['won'].

It's not JSON at all, just a normal array. Trailing commas are bad form but work in most JS engines. — JJJ
– JJJ, Commented Jun 25, 2014 at 9:29
I just added the basic JSON, its not an actual JSON structure. ArrLa is just a variable.... Declared all the variables without var keyword — user1853128
– user1853128, Commented Jun 25, 2014 at 9:30

Ingmars · Accepted Answer · 2014-06-25 12:53:48Z

2

Since your Q is flagged as jquery, you can do this:

var cat = [
    {
        view: [
            {
                ent: [
                    {
                        data: [
                            {
                                key: "id",
                                value: "00"
                            }, 
                            {
                                key: "cid",
                                value: "123"
                            }
                        ],
                        label: "joy"
                    }, 
                    {
                        key: "id",
                        value: "11"
                    }, 
                    {
                        key: "cid",
                        value: "234"
                    }
                ], // end ent
                label: "won"
            }, 

        ] //end view
    }
];

var labels = [];

$.map( cat, function flattener( node ) {
    if ( $.isPlainObject( node ) && node.hasOwnProperty('label') ) {
        labels.push( node.label );
    }
    return ($.isArray( node ) || $.isPlainObject( node )) ? $.map( node, flattener) : node;
} );

console.log( labels );

Fiddle: http://jsfiddle.net/fFwQ6/

Thing to note is that order will be dictated by depth: deeper labels come last.

UPDATE: It is easy to turn it into an utility function:

function grabKeys( source, keyName ) {
    var values = [];

    $.map( source, function flattener( node ) {
        if ( $.isPlainObject( node ) && node.hasOwnProperty(keyName) ) {
            values.push( node[keyName] );
        }
        return ($.isArray( node ) || $.isPlainObject( node )) ? $.map( node, flattener) : node;
    } );

    return values;
}


var labels = grabKeys( cat, 'label' );
var cids = grabKeys( cat, 'cid' );

UPDATE 2: Since 'cid' is a key value and not a name, we must use a slightly different method. Sorry I did not noticed it previously.

function grabPairedKeys( source, keyValue, keyName1, keyName2 ) {
    keyName1 = keyName1 || 'key';
    keyName2 = keyName2 || 'value';

    var values = [];

    $.map( source, function flattener( node ) {
        if ( $.isPlainObject( node ) && node.hasOwnProperty(keyName1) && node.hasOwnProperty(keyName2) && node[keyName1] === keyValue ) {
            values.push( node[keyName2] );
        }
        return ($.isArray( node ) || $.isPlainObject( node )) ? $.map( node, flattener) : node;
    } );

    return values;
}


var labels = grabKeys( cat, 'label' );
var cids = grabPairedKeys( cat, 'cid' );

edited Jun 25, 2014 at 12:53

answered Jun 25, 2014 at 10:17

Ingmars

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3 Comments

user1853128 Over a year ago

Thank you very much brother, your code is very minimal and gives the accurate values. If I need to have the value for the key "cid" along with label how to modify the code.

user1853128 Over a year ago

Thank you very much once again.... Expected output should be cid:["234","123"] and label:["won","joy"]. I am getting output only for label but not for cid, I changed the code of your previous fiddle and tried by replacing it with the updated one. Can you please attach the fiddle of expecting result. I am very much thankful to you....

Ingmars Over a year ago

Update 2 added. There was a small misconception.

Indranil Mondal · Accepted Answer · 2014-06-25 09:56:05Z

1

You should use the push in the loop.

    for(var i=0;i<ArrL.length;i++){
                ArrF = ArrL[i].view;
                for(var j=0;j<ArrF.length;j++){
                    ArrE = ArrF[j].ent;
                    for(var k=0;k<ArrE.length;k++){
                        ArrLa = ArrE[k].label;
                        Array.push(ArrLa);
                    }

                }

            }

answered Jun 25, 2014 at 9:56

Indranil Mondal

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Comments

Bergi · Accepted Answer · 2014-06-25 09:58:01Z

1

Well, you only push the last value that was assigned to ArrLa after having iterated the view array. Instead, push the value right away when you encounter it:

var Array = [];
for(var i=0;i<ArrL.length;i++){
    var ArrF = ArrL[i].view;
    for(var j=0;j<ArrF.length;j++){
        var ArrE = ArrF[j].ent;
        for(var k=0;k<ArrE.length;k++){
             Array.push(ArrE[k].label);
        }
    }
}
console.log(Array);

answered Jun 25, 2014 at 9:58

Bergi

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