Adding properties dynamically in javascript

Question

In Javascript you add properties to an object dynamically for example:

var car = {colour: "blue"};
car.reg = "XYXABC00D";

Is there a special buzzword for this?

Thanks.

Are you just looking for a single word that means "dynamically adding a property to an object"? — Peter Olson, Mar 16 '12 at 21:37

score 2 · Answer 1 · edited May 23 '17 at 12:11

2

Your buzzword might be called the expando.

Javascript expando objects

Well, in javascript, any object is an expando object. What it means is, as the article covers, that whenever you try to access a property it will automatically be created.

In practice the name "expando" is only used when a dynamic property added to a DOM node, which made "funny" things in ancient Internet Explorer versions.

edited May 23 '17 at 12:11

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answered Mar 16 '12 at 21:41

biziclop

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I'm not sure what you mean by "In practice it is only used when a dynamic property is added to a DOM node". I dynamically add keys to objects quite frequently... – Peter Olson Mar 16 '12 at 21:46
Sorry, I meant that the expression "expando" is generally used in DOM context, especially when IE memory leaks are discussed. – biziclop Mar 16 '12 at 21:49
What's the word to cover the programming technique when there is no DOM? – dublintech Mar 16 '12 at 21:50
What's wrong with "I added a `date` property to object `o`"? :) – biziclop Mar 16 '12 at 21:54

score 0 · Answer 2 · answered Mar 16 '12 at 22:12

Since objects in javascript are associative arrays, adding a dynamic property is simply mapping a key/value pair. So perhaps the technical term you're looking for is probably related to assigning/mapping (terms that are related to associative arrays instead of the dynamic object).

Adding properties dynamically in javascript

2 Answers2