FOIT and FOUT

The acronym FOIT stands for Flash of Invisible Text. It refers to a web performance issue that occurs when web fonts are being loaded. During this period, the browser hides the text until the font files are fully downloaded and ready to be displayed. This results in a temporary but noticeable absence of text on the screen, which can be confusing or frustrating for users.

It's helpful to understand FOIT in contrast to FOUT (Flash of Unstyled Text):

FOIT (Flash of Invisible Text):: Text is invisible until the web font is fully loaded. This can lead to a period where the user sees a blank space where text should be, which impacts readability and user experience.
FOUT (Flash of Unstyled Text):: Text is displayed immediately using a fallback font, and then swapped with the web font once it loads. This can cause a brief visual change but ensures that text is always visible.

Applying the strategies below can minimize the impact of FOIT and ensure a smoother, more visually consistent experience for users as web fonts load.

Managing FOIT and FOUT

There are several effective strategies for mitigating FOIT and managing FOUT:

Font Loading Strategies

Font Display Property: Use the font-display property in CSS to control the rendering behavior of web fonts. Setting it to swap, fallback, or optional can help manage FOIT and FOUT.

@font-face {
font-family: 'MyWebFont';
src: url('/path/to/font.woff2') format('woff2');
font-display: swap; /* Use swap to prevent FOIT */
}

Preload Fonts

Use the <link rel="preload"> attribute to preload font resources, ensuring they are prioritized and loaded earlier in the page lifecycle.

<link rel="preload" href="/path/to/font.woff2" as="font" type="font/woff2" crossorigin="anonymous">

Inline Critical Fonts

Inline critical font styles directly in the HTML document's <head> to reduce initial load time and ensure text is visible as soon as possible.