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Ilya Kantor 2016-08-05 16:53:08 +03:00
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1-js/4-object-basics/01-object/article.md
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@ -490,13 +490,13 @@ alert(*!*user.name*/!*); // 'Pete', changes are seen from the "user" reference
The example above demonstrates that there is only one object. Like if we had a cabinet with two keys and used one of them (`admin`) to get into it -- later using the other one (`user`) we will see things modified.
### Comparison by reference
The equality `==` and strict equality `===` operators for objects work exactly the same, simple way.
The equality `==` and strict equality `===` operators for objects work exactly the same.
**Two object variables are equal only when reference the same object.**
**Two objects are equal only if they are the same object.**
For instance, two variables reference the same object, they are equal:
```js run
let a = {};
@ -506,9 +506,7 @@ alert( a == b ); // true, both variables reference the same object
alert( a === b ); // true
```
In all other cases objects are non-equal, even if their content is the same.
For instance:
And here two independent objects are not equal, even though both are empty:
```js run
let a = {};
@ -517,9 +515,7 @@ let b = {}; // two independent objects
alert( a == b ); // false
```
That rule only applies to object vs object equality checks.
For other comparisons like whether an object less/greater than another object (`obj1 > obj2`) or for a comparison against a primitive `obj == 5`, objects are converted to primitives. We'll study how object conversions work very soon, but to say the truth, such comparisons occur very rarely in real code and usually are a result of a coding mistake.
For comparisons like `obj1 > obj2` or for a comparison against a primitive `obj == 5`, objects are converted to primitives. We'll study how object conversions work very soon, but to say the truth, such comparisons occur very rarely in real code and usually are a result of a coding mistake.
## Cloning and merging, Object.assign