Add property to each object in the array [duplicate]

Question

I'm trying to add a property to each object in the array:

var capitals = [{
    country: "What's the capital of Ecuador?",
    choices: ["Quito", "Caracas", "Panama", "Loja"],
    corAnswer: 0
}, {
    country: "What is the capital of China?",
    choices: ["Shanghai", "Beijing", "Ghangzou", "Hong Kong"],
    corAnswer: 0
}];

Should become:

var capitals = [{
        country: "What's the capital of Ecuador?",
        choices: ["Quito", "Caracas", "Panama", "Loja"],
        corAnswer: 0,
        global: true
    }, {
        country: "What is the capital of China?",
        choices: ["Shanghai", "Beijing", "Ghangzou", "Hong Kong"],
        corAnswer: 0,
        global: true
    }];

The array can contain multiple objects. What kind of function do I need?

Rajaprabhu Aravindasamy · Accepted Answer · 2016-04-06 11:15:31Z

13

You have to use forEach at this context,

capitals.forEach(function(itm){
 itm.global = true;
});

If you are not familiar with the usage of forEach, then you can do the same job by using a for loop.

for(var i=0,len=capitals.length;i<len;i++){
  capitals[i].global = true;
}

edited Apr 6, 2016 at 11:15

answered Apr 6, 2016 at 11:14

Rajaprabhu Aravindasamy

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4 Comments

Vladimir Starkov Over a year ago

i'd suggest to use .map to not mutate original array of objects

Rajaprabhu Aravindasamy Over a year ago

@VladimirStarkov That will create a clone unnecessarily. This context does not require map, I believe.

Vladimir Starkov Over a year ago

OP didnt say anything about context, using map provide you explicit data flow instead of implicit one with forEach

Vladimir Starkov Over a year ago

const capital = [{}, …].map(i => { i.global = true; return i; }) thats it

Easwar Raju · Accepted Answer · 2016-04-06 11:16:41Z

-1

If you do not have to support legacy browsers, then you could use Array.prototype.map

answered Apr 6, 2016 at 11:16

Easwar Raju

2831 silver badge5 bronze badges

1 Comment

adamdport Over a year ago

Downvoted because you didn't attempt to answer the question. A good answer would show how to use that function in the context of this question.

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