The display property of the FontFace interface determines how a font face is displayed based on whether and when it is downloaded and ready to use. This property is equivalent to the CSS font-display descriptor.

When this property is used, font loading has a timeline with three periods. The lengths of the first two periods depend on the value of the property and the user agent. (See below.)

block period

The browser invisibly prepares a fallback font. If the font face loads during this time, it's used to display the text and display is complete.

swap period

If the font face is still not loaded, the fallback font will be shown. When the font face loads, the fallback will be swapped for the downloaded font.

failure period

If the font face still is not loaded, the fallback font will be shown and no swap will occur.

A string with one of the following values.

auto

Use the font display strategy provided by the user agent.

block

Gives the font face a short block period and an infinite swap period. The spec recommends 3 seconds for the block period, though this may vary from browser to browser.

fallback

Gives the font face a short block period and a short swap period. The spec recommends 100 ms or less for the block period and 3 seconds for the swap period, though these values may vary from browser to browser.

optional

Gives the font face a short block period and no swap period. The spec recommends 100 ms or less, though this may vary from browser to browser.

swap

Gives the font face a 0 second block period and an infinite swap period.