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Script defer Property

Script Object Reference Script Object

Example

Find out if a script was executed when a page was finished parsing:

var x = document.getElementById("myScript").defer

The result of x will be:

true
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Definition and Usage

The defer property sets or returns whether a script should be executed when a page has finished parsing, or not.

This property reflects the defer attribute of the <script> tag.

Note: The defer attribute is only for external scripts (and should only be used if the src attribute is present).

Note: There are several ways an external script can be executed:

  • If async is present: The script is executed asynchronously with the rest of the page (the script will be executed while the page continues the parsing)
  • If async is not present and defer is present: The script is executed when the page has finished parsing
  • If neither async or defer is present: The script is fetched and executed immediately, before the browser continues parsing the page

Browser Support

Internet Explorer Firefox Opera Google Chrome Safari

The defer property is supported in all major browsers.

Note: The defer attribute is not supported in Opera 12 and earlier versions.


Syntax

Return the defer property:

scriptObject.defer

Set the defer property:

scriptObject.defer=true|false

Property Values

Value Description
true|false Specifies whether a script should be executed when the page has finished parsing, or not
  • true - The script is executed when the page has finished parsing
  • false - The script will not be executed when the page has finished parsing

Technical Details

Return Value: A Boolean, returns true if the script is executed when the page has finished parsing, otherwise it returns false

Related Pages

HTML reference: HTML <script> defer attribute


Script Object Reference Script Object