英語 での The global object の使用例とその 日本語 への翻訳
{-}
-
Colloquial
-
Ecclesiastic
-
Computer
-
Programming
By specification, this in this case must be the global object, even in non-browser environments like Node. JS.
Any message sent to bounce within Max will attempt to set properties of the Global object using that name.
If it is not provided, or is null, the global object associated with callback is used instead. forEach does not mutate the array on which it is called.
This algorithm assumes the knowledge of a set of objects called roots(In JavaScript, the root is the global object).
Previously, global variables defined with those statements could be accessed as properties on the global object(window or this in the global scope) like global variables defined with var.
Foo;// Returns: true After defining a Global Variable foo, we can access its value directly from the window object, by using the variable name foo as a property name of the Global Object window. foo.
In an install script, there is no associated window, however the global object will be an Install object which contains a number of functions to customize the install process.
No matter what, foo's this is set to what it was when it was created(in the example above, the global object).
While the above example might still appear to work in some cases, due to the workings of this in JavaScript, it will use the global object as the value of this.
Not only is automatic boxing a performance cost, but exposing the global object in browsers is a security hazard, because the global object provides access to functionality that"secure" JavaScript environments must restrict.
So, as we have noted, in case when on the left hand side of call parentheses there is a value not of Reference type but any another type, this value is automatically set to null and, as consequence, to the global object.
In the above code example, function B's this is set to function A's this which is obj, so it remains set to obj even when called in a manner that would normally set its this to undefined or the global object or any other method as in the previous example in the global execution context.
In web browsers, the window object is also the global object.
In the global code, this value is always the global object itself.
In JavaScript, the document is accessible the same way it has been in older browsers: from the document property of the global object.
As a practical difference, global let/const variables are definitively properties of the global Environment Record, but they do not exist in the global object.
In non-strict mode the value of this in such case will be the global object(window in a browser, we will get to it later in the chapter Global object). .
And there's a global object that provides some of the global variables.