Couldn't add new property to objects in JavaScript array

Question

Am trying to add a new field (sid) in each object in a JavaScript array:

dataset_sk_final = [
  {'id':0,'name':'Banking'},
  {'id':1,'name':'Home'},
  {'id':2,'name':'Travel'}
]

My output should be like -

dataset_sk_final = [
  {'id':0,'name':'Banking','sid':''},
  {'id':1,'name':'Home','sid':''},
  {'id':2,'name':'Travel','sid':''}
]

I tried using below code but its not working, what am I missing?

var dataset_sk_final1 = [];
object.keys(dataset_sk_final).foreach(function (key) {
  'sid' = ''
}
dataset_sk_final1.push(dataset_sk_final[key]);

alert('after assigning final:'+json.stringify(dataset_sk_final1),null,2);

What does your console show? First, it will error out on object.keys, which needs to be Object.keys. Second, it will error out on 'sid'='', which is invalid syntax and doesn't mean anything--what did you expect that to do? Third, it will error out on the push line, since you are referring to key, which does not exist in this scope. Also, not that this problem has nothing to do with JSON. It's just a plain old JavaScript object. — user663031
– user663031, Commented Dec 10, 2015 at 19:00

Oleksandr T. · Accepted Answer · 2015-12-10 18:59:55Z

1

First off in Array object there is no method foreach but there is forEach (case sensitive), second - to assign new property to Object you can use dot notation like el.sid = '' or bracket notation like el['sid'] = '' but not 'sid'='' because it is just String

var dataset_sk_final = [
  {'id':0,'name':'Banking'},
  {'id':1,'name':'Home'},
  {'id':2,'name':'Travel'}
];

dataset_sk_final.forEach(function (el) {
  el.sid = '';
});

console.log(JSON.stringify(dataset_sk_final, null, 2));

edited Dec 10, 2015 at 18:59

answered Dec 10, 2015 at 18:54

Oleksandr T.

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Comments

Ajwhiteway · Accepted Answer · 2015-12-11 00:29:07Z

0

This should work?

for(var index in data_sk_final) {
    data_sk_final[index].sid = ''
}

so your example becomes

dataset_sk_final = [
  {'id':0,'name':'Banking'},
  {'id':1,'name':'Home'},
  {'id':2,'name':'Travel'}
]

for(var index in data_sk_final) {
    data_sk_final[index].sid = ''
}

alert('after assigning final:'+json.stringify(dataset_sk_final),null,2);

edited Dec 11, 2015 at 0:29

answered Dec 10, 2015 at 18:54

Ajwhiteway

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1 Comment

Heretic Monkey Over a year ago

Please add some explanation of why this code helps the OP. This will help provide an answer future viewers can learn from. See How to Answer for more information.

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