JavaScript - Object
// JavaScript - Objects
Different way to create objects:
var obj = new Object();
var obj = {};
var car = { color: 'red', wheels: 4, hubcaps: 'spinning', age: 4};
These are sematically equivalent; the second is called object literal syntax,
and is more convenient. Object literal syntax was not present in very early
versions of the language.
Different ways to access an object's property / attribute:
obj.name = "Simon";
var name = obj.name;
obj["name"] = "Simon";
var name = obj["name"];
These are sematically equivalent. The square-brackets method has the advantage
that the name of the property is provided as a string, which means it can be
calculated at run-time. It can also be used to set and get properties with
names that are reserved words:
obj.for = "Simon"; // Syntax error
obj["for"] = "Simon"; // works fine
Objects in JavaScript are mutable keyed collections. In JavaScript, arrays are
objects. Functions are objects. Regular expressions are objects. Objects are
objects.
An object is a container of properties, where a property has a name and a value.
A property name can be any string, including the empty string. A property
value can be any JavaScript value except for undefined.
Object literals are a convenient notation for specifying new objects. The names
of the properties can be specified as names or as strings. The names are
treated as literal names, not as variable names, so the names of the properties
of the object must be known at compile time. The values of the properties are
expressions.
page revision: 3, last edited: 14 Nov 2016 18:31