Convert array from with keys to without keys

Question

Is there an elegant way to convert the following json data to the desired data format below?

original data

{
   "data": [
        {
            "timestamp": 1385118121279,
            "value": 40
        },
        {
            "timestamp": 1385118301279,
            "value": 7
        }

    ]
}

desired format

[[1385118121279,40],[1385118301279,7]]

Yes, it's very easy with a simple for statement, or use .map() if you prefer. — cookie monster
– cookie monster, Commented Jan 7, 2014 at 5:12

Edgar Villegas Alvarado · Accepted Answer · 2014-01-07 05:49:41Z

1

Yes, with this:

var transformed = originalObj.data.map(function(item){
   return [item.timestamp, item.value];
});

However, doesn't work in old browsers.

For all browsers including old ones:

var transformed = [];
for(var i in originalObj.data){
    var item = originalObj.data[i];
    transformed.push([item.timestamp, item.value]);
}

Cheers

edited Jan 7, 2014 at 5:49

answered Jan 7, 2014 at 5:12

Edgar Villegas Alvarado

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3 Comments

jasonscript Over a year ago

for support in older browsers, jQuery also provides a map function

Edgar Villegas Alvarado Over a year ago

That's right. And many frameworks, too. But the asker didn't mention jQuery, also it's not in the question tags. Cheers ;)

jasonscript Over a year ago

agreed. Just adding the comment for those who have to support older browsers (like me)

Aks · Accepted Answer · 2014-01-07 05:22:19Z

0

This can be done by iterating over object and we can get the array we want.

var abc ={
   "data": [
        {
            "timestamp": 1385118121279,
            "value": 40
        },
        {
            "timestamp": 1385118301279,
            "value": 7
        }

    ]
};
var dataArray = [];
for (var key in abc.data) {
      if(abc.data.hasOwnProperty(key)){
        dataArray.push(abc.data[key].timestamp);
      }
}
console.log(dataArray);

answered Jan 7, 2014 at 5:22

Aks

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Comments

Passerby · Accepted Answer · 2014-01-07 05:36:58Z

I'm not sure if this is "elegant", but anyway:

function obj2arr(obj){
    if(obj instanceof Array){
        var ret=[];
        for(var i=0;i<obj.length;i++){
            if(typeof obj[i]=="object"){
                ret.push(obj2arr(obj[i]));
            }else{
                ret.push(obj[i]);
            }
        }
        return ret;
    }else if(typeof obj=="object"){
        var ret=[];
        var keys=Object.getOwnPropertyNames(obj);
        for(var i=0;i<keys.length;i++){
            if(typeof obj[keys[i]]=="object"){
                ret.push(obj2arr(obj[keys[i]]));
            }else{
                ret.push(obj[keys[i]]);
            }
        }
        return ret;
    }else{
        return obj;
    }
}

The following test:

console.log(obj2arr({
    "data": [{
        "timestamp": 1385118121279,
        "value": 40
    },{
        "timestamp": 1385118301279,
        "value": 7
    }]
}));

Outputs:

[ [ [ 1385118121279, 40 ], [ 1385118301279, 7 ] ] ]

Online demo (I'm surprised to see that the JS engine in Ideone doesn't support Object.getOwnPropertyNames)

Although please be noted that this is a recursive solution, so big objects may causes stack overflow...

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