Properties
最后更新于:2022-04-01 03:12:46
# Properties
Object's property is a `propertyName`: `propertyValue` pair, where **property name can be only a string**. If it's not a string, it gets casted into a string. You can specify properties **when creating** an object **or later**. There may be zero or more properties separated by commas.
~~~
var language = {
name: 'JavaScript',
isSupportedByBrowsers: true,
createdIn: 1995,
author:{
firstName: 'Brendan',
lastName: 'Eich'
},
// Yes, objects can be nested!
getAuthorFullName: function(){
return this.author.firstName + " " + this.author.lastName;
}
// Yes, functions can be values too!
};
~~~
The following code demonstates how to **get** a property's value.
~~~
var variable = language.name;
// variable now contains "JavaScript" string.
variable = language['name'];
// The lines above do the same thing. The difference is that the second one lets you use litteraly any string as a property name, but it's less readable.
variable = language.newProperty;
// variable is now undefined, because we have not assigned this property yet.
~~~
The following example shows how to **add** a new property **or change** an existing one.
~~~
language.newProperty = 'new value';
// Now the object has a new property. If the property already exists, its value will be replaced.
language['newProperty'] = 'changed value';
// Once again, you can access properties both ways. The first one (dot notation) is recomended.
~~~