The Document.open() method opens a document for writing.

This does come with some side effects. For example:

• All event listeners currently registered on the document, nodes inside the document, or the document's window are removed.
• All existing nodes are removed from the document.

None.

A Document object instance.

The following simple code opens the document and replaces its content with a number of different HTML fragments, before closing it again.

document.open();
document.write("<p>Hello world!</p>");
document.write("<p>I am a fish</p>");
document.write("<p>The number is 42</p>");
document.close();

An automatic document.open() call happens when document.write() is called after the page has loaded.

This method is subject to the same same-origin policy as other properties, and does not work if doing so would change the document's origin.

There is a lesser-known and little-used three-argument version of document.open(), which is an alias of Window.open() (see its page for full details).

This call, for example opens github.com in a new window, with its opener set to null:

document.open("https://www.github.com", "", "noopener=true");

Browsers used to support a two-argument document.open(), with the following signature:

document.open(type, replace);

Where type specified the MIME type of the data you are writing (e.g. text/html) and replace if set (i.e. a string of "replace") specified that the history entry for the new document would replace the current history entry of the document being written to.

This form is now obsolete; it won't throw an error, but instead just forwards to document.open() (i.e. is the equivalent of just running it with no arguments). The history-replacement behavior now always happens.

• Document
• Window.open()