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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

Property
defer Yes Yes Yes Yes Yes

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