EN
JavaScript - add new item to object at specific position
3 points
In this article, we would like to show you how to add a new item to object at a specific position in JavaScript.
Runnable example:
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function insertProperty(obj, key, value, position) {2
var result = {};3
var counter = 0;4
for (var prop in obj) {5
if (obj.hasOwnProperty(prop)) {6
if (counter === position) {7
result[key] = value;8
}9
result[prop] = obj[prop];10
counter++;11
}12
}13
if (!(key in result)) {14
result[key] = value;15
}16
return result;17
};18
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// Usage example:21
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var oldUser = { name: 'John', age: 30, hobby: 'football'};23
var newUser = insertProperty(oldUser, 'email', 'johnh@email.com', 2); // position from 024
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console.log('Old user: ' + JSON.stringify(oldUser, null, 4));26
console.log('New user: ' + JSON.stringify(newUser, null, 4));Explanation how it works:
- To add a new item to an object we need to create a new empty object and a
counterfor object position since objects don't have an index. - We loop through the original object until the
countervalue equals thepositionwe want to insert the newkey/valuepair. - When it does, we push the new
key/valuepair to the new object and loop through the rest of the original object's items.
Note:
This approach is suboptimal because it needs to rewrite the entire object.
