JavaScript Window Properties
Index
About This Index
This page is the JavaScript Window Properties index for the tutorial track. Each row is a value you read on window. There is no separate tutorial file for these properties, so the description lives here.
Learn what the window is on /js/window. Functions such as alert() and setTimeout() are on the methods index.
No parentheses.
window.innerWidth is a number. window.closed is true or false. window.innerWidth() throws.
Syntax
How to Read a Window Property
Properties are values. No parentheses:
JavaScript
window.self === window; // true
window.closed; // false while the tab is open
window.innerWidth; // viewport width
window.scrollY; // pixels scrolled down
window.location.href; // full URL
window.localStorage; // Storage for this originBrowse
JavaScript Window Properties Table
Properties you read on window in this JavaScript tutorial (21 entries).
This window and its frames
8 propertiesRead these on window to see which window you are in, and whether it sits inside a frame.
| Property | Description | Guide |
|---|---|---|
self | This window. window.self === window is true. | On this page |
name | The window’s name string. It is "" unless the window or iframe was given a name. | On this page |
closed | false while you can still use the window. true after that window has been closed. | On this page |
opener | The window that called open(), or null when the reader opened this tab. | On this page |
parent | The parent window. On a top-level page, parent === window. | On this page |
top | The topmost window. On a top-level page, top === window. | On this page |
length | How many child frames this window contains. A page with no iframes has length 0. | On this page |
frameElement | The iframe element that contains this window, or null on a top-level page. | On this page |
Size and scroll position
6 propertiesNumbers, in CSS pixels. Read them with no parentheses.
| Property | Description | Guide |
|---|---|---|
innerWidth | Width of the viewport, the area inside the window where the page is drawn. | On this page |
innerHeight | Height of the viewport, the area inside the window where the page is drawn. | On this page |
outerWidth | Width of the whole browser window, including the browser’s own bars. | On this page |
outerHeight | Height of the whole browser window, including the browser’s own bars. | On this page |
scrollX | How many pixels the document is scrolled horizontally. pageXOffset is the same value. | On this page |
scrollY | How many pixels the document is scrolled vertically. pageYOffset is the same value. | On this page |
The page this window shows
7 propertiesObjects the window keeps for the document, the URL, history, and storage.
| Property | Description | Guide |
|---|---|---|
document | The page. window.document is the tree you search with querySelector and getElementById. | On this page |
location | The URL of this window. location.href is the full address. Assigning it navigates the page. | On this page |
history | The session history for this tab. history.back() goes to the previous entry. | On this page |
navigator | The browser. navigator.userAgent is one string it exposes. | On this page |
screen | The display. screen.width and screen.height are the screen size in pixels. | On this page |
localStorage | A Storage object for this origin that keeps keys after the tab closes. | On this page |
sessionStorage | A Storage object for this origin that lasts until this tab closes. | On this page |
Frequently Asked Questions
Window properties are values on the window object. innerWidth and scrollY are numbers. closed is true or false. document, location, history, localStorage, and sessionStorage are objects. alert() and setTimeout() are methods, not properties.
The Window page teaches what the browser tab object is, with examples for self, location.href, and a timer id. This Properties index lists the values you read. Method tutorials are on the Window Methods index.
You read it with no parentheses: window.innerWidth. That number is the viewport width in CSS pixels. window.innerWidth() throws, because a number is not a function.
It is the number of child frames, such as iframes, in this window. A page with no frames has length 0. It is not the length of the URL or of localStorage.
If you are new, read JavaScript Window first. Then open the Window Methods index for alert(), setTimeout(), and open().
Call a method next
Properties are values. alert() and setTimeout() are functions.
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