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simplefocus/flowtype.js

★ 4,572JavaScriptAudience · developerComplexity · 1/5LicenseSetup · easy

TLDR

A jQuery plugin that automatically scales font size based on element width to keep text at a readable line length across all screen sizes, though plain CSS fluid typography now achieves the same effect.

Mindmap

mindmap
  root((repo))
    What It Does
      Scale font by width
      Readable line length
      All screen sizes
    How to Use
      Include jQuery
      Call one function
      Set CSS base size
    Options
      fontRatio setting
      Min max thresholds
    Status
      CSS alternative exists
      MIT licensed
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Things people build with this

USE CASE 1

Add responsive font scaling to a legacy website that already uses jQuery.

USE CASE 2

Keep text at a comfortable reading width on both wide desktop screens and narrow mobile screens.

USE CASE 3

Set font size breakpoints so scaling stops at a defined minimum or maximum element width.

Tech stack

JavaScriptjQuery

Getting it running

Difficulty · easy Time to first run · 5min

Requires jQuery to be included on the page, set a CSS base font size as a fallback for visitors with JavaScript disabled.

MIT license, use, modify, and distribute freely for any purpose including commercial projects.

In plain English

FlowType.JS is a jQuery plugin that automatically adjusts the font size on a web page based on how wide the containing element is. The goal is to keep text at a readable line length, roughly 45 to 75 characters per line, across all screen sizes. Without something like this, setting a fixed font size often results in lines that are either too long on wide screens or too short on narrow ones. The plugin works by measuring the width of a target element, then computing and setting a font size that produces a good character count at that width. You apply it by calling a single jQuery function on any element, and all child elements inside it are updated as well. The fontRatio option controls how aggressively the font scales, and you can set minimum and maximum width thresholds so the scaling stops at certain breakpoints. Installation requires including jQuery and the FlowType.JS script on your page, setting a base font size in CSS so the page still works for visitors with JavaScript disabled, and then calling the plugin before the closing body tag. The README includes step-by-step setup instructions and code examples for common configurations. There is an important note at the top of the README: as of 2021, the same effect can be achieved with plain CSS using what is called fluid typography, and the README links to a CSS-only approach. This means FlowType.JS is essentially a historical tool that solved a problem that CSS has since addressed natively. The plugin is licensed under the MIT license. Line-height support was removed in version 1.1 and the README recommends using unitless line-height values directly in CSS instead.

Copy-paste prompts

Prompt 1
Show me how to add FlowType.JS to an existing HTML page that uses jQuery to make the main article font scale responsively.
Prompt 2
How do I set the fontRatio option in FlowType.JS to make font sizes scale more aggressively on wide screens?
Prompt 3
What CSS-only alternative to FlowType.JS can I use in a modern browser without jQuery?
Prompt 4
Configure FlowType.JS to only scale fonts when the container is between 500px and 1200px wide.
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