Add new attribute (element) to JSON object using JavaScript
Add new attribute (element) to JSON object using JavaScript
Popular Answer
JSON stands for JavaScript Object Notation. A JSON object is really a string that has yet to be turned into the object it represents.
To add a property to an existing object in JS you could do the following.
object["property"] = value;
or
object.property = value;
If you provide some extra info like exactly what you need to do in context you might get a more tailored answer.
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var jsonObj = {
members:
{
host: "hostName",
viewers:
{
user1: "value1",
user2: "value2",
user3: "value3"
}
}
}
var i;
for(i=4; i<=8; i++){
var newUser = "user" + i;
var newValue = "value" + i;
jsonObj.members.viewers[newUser] = newValue ;
}
console.log(jsonObj);
A JSON object is simply a javascript object, so with Javascript being a prototype based language, all you have to do is address it using the dot notation.
mything.NewField = 'foo';
thanks for this post. I want to add something that can be useful.
For IE, it is good to use
object["property"] = value;
syntax because some special words in IE can give you an error.
An example:
object.class = 'value';
this fails in IE, because "class" is a special word. I spent several hours with this.
With ECMAScript since 2015 you can use Spread Syntax ( …three dots):
let people = { id: 4 ,firstName: 'John'};
people = { ...people, secondName: 'Fogerty'};
It's allow you to add sub objects:
people = { ...people, city: { state: 'California' }};
the result would be:
{
"id": 4,
"firstName": "John",
"secondName": "Forget",
"city": {
"state": "California"
}
}
You also can merge objects:
var mergedObj = { ...obj1, ...obj2 };
You can also use Object.assign
from ECMAScript 2015
. It also allows you to add nested attributes at once. E.g.:
const myObject = {};
Object.assign(myObject, {
firstNewAttribute: {
nestedAttribute: 'woohoo!'
}
});
Ps: This will not override the existing object with the assigned attributes. Instead they'll be added. However if you assign a value to an existing attribute then it would be overridden.