Where are constructors such as, `new Image()` and `new Option()`, documented?

by

There is a distinction between JavaScript™ (the implementation of ECMAScript for DOM manipulation by Mozilla, aka Gecko) and the generic term “javascript” that is used to describe similar scripting environments in other browsers (e.g. JScript in IE).

Archaic documentation,
[…]
describes the existence of these constructors implicating them as
intrinsic JavaScript language components, which is incorrect.

How do you come to that conclusion? JavaScript™ belongs to Mozilla so they can specify that it contains whatever they want. JavaScript™ has had an Image and Option constructor since the very beginning, other implementations have copied them so that every browser in existence has them. Such features existed before the creation of the W3C DOM interfaces and, where ubiquitous, are labelled “DOM 0”, which really means were supported by Netscape Navigator and Internet Explorer at the time of DOM 1.

DOM 0 is not officially documented anywhere. HTML5 is an attempt at writing a specification for HTML and javascript as is implemented in browsers, so it includes both the Image and Option constructors and so includes DOM 0 features, but they aren’t labelled or classified as such.

[…]

Yet, these constructors are clearly not intrinsic to the language
specification of JavaScript

There is no published specification for JavaScript™, there is only the JavaScript documentation at Mozilla Developer Network (MDN). Also note that the documentation at MDN is a public wiki that anyone can create and edit, including you. 🙂

You are mistaken in believing that the documentation at Mozilla is some kind of complete specification for JavaScript™—it isn’t. Not by a long way. It is really just documentation that has been added by interested persons, mostly by poking around the browser and seeing what it does. There is also a JavaScript Reference, but you may also find that lacking.

[…]

HTMLImageElement Mozilla documentation

That link to the the Gecko DOM reference documents the JavaScript implementation of the W3C HTMLImageElementInterface which does not have an Image constructor.

Contemporary precedent for Image() constructor use at Mozilla

Which indicates that it exists, but there is no convenient place to document it. It might be best documented in the JavaScript Reference. If you wish to add it, get an MDN account (free, very easy) and add it.

Edit

There is now an Image article at MDN that links to relevant standards.

Edit 25 May 2015

The Option constructor is documented in HTML5.

More Related Contents:

  1. Executing elements inserted with .innerHTML
  2. How to stop event propagation with inline onclick attribute?
  3. document.createElement(“script”) synchronously
  4. When does reflow happen in a DOM environment?
  5. Firing event on DOM attribute change
  6. How to expose IFrame’s DOM using jQuery?
  7. How can I simulate a click to an anchor tag?
  8. How To Wrap / Surround Highlighted Text With An Element
  9. Finding line-wraps
  10. Get child node index
  11. Getting value of HTML Checkbox from onclick/onchange events
  12. Check if option is selected with jQuery, if not select a default
  13. Select all elements with a “data-xxx” attribute without using jQuery
  14. DOM refresh on long running function
  15. Finding DOM node index
  16. change html text from link with jquery
  17. Wait for iframe to load in JavaScript
  18. Why does getElementById not work on elements inside the document element? [duplicate]
  19. Jquery Event Not Triggering for DOM Elements Created after page load [duplicate]
  20. Add a link stylesheet dynamically in the [closed]
  21. How to inherit from the DOM element class
  22. DOM Mutation event in JQuery or vanilla Javascript
  23. forEach method of Node.childNodes?
  24. Get elements from page.evaluate in Puppeteer? [duplicate]
  25. Getting HTML elements by their attribute names
  26. Display DIV at Cursor Position in Textarea [duplicate]
  27. Get immediate first child element
  28. How can I replace one class with another on all elements, using just the DOM?
  29. Is there a way to know if a link/script is still pending or has it failed
  30. Removing element with jQuery?

Leave a Comment