use-fit-text

React hook that iteratively adjusts the font size so that text will fit in a div.

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  • checks if text is overflowing by using scrollHeight and offsetHeight
  • recalculates when container is resized (using (polyfilled) ResizeObserver)
  • recalculates when content changes
  • uses binary search; with default options, makes a maximum of 5 adjustments with a resolution of 5% font size from 20-100%
  • < 4 kB minified + gzipped
  • written in TypeScript

Installation

npm install --save use-fit-text

Usage

import React from "react";
import useFitText from "use-fit-text";

function Example() {
  const { fontSize, ref } = useFitText();

  return (
    <div ref={ref} style={{ fontSize, height: 40, width: 100 }}>
      Lorem ipsum dolor sit amet, consectetur adipiscing elit.
    </div>
  );
}

Demo / example code

API

useFitText(options)

  • Returns an object with the following properties:

    • fontSize (string) - the font size as a string (CSS percent) to be passed as the fontSize property of the style prop of the div
    • ref (React.MutableRefObject<HTMLDivElement>) - the ref to be passed to the ref attribute of the div

  • options (optional) - an object with the following optional properties:

    • maxFontSize (number, default: 100) - maximum font size in percent
    • minFontSize (number, default: 20) - minimum font size in percent
    • onFinish ((fontSize: number) => void, default: undefined) - function that is called when resizing
      finishes. The final fontSize is passed to the function as an argument.
    • onStart (() => void, default: undefined) - function that is called when resizing starts
    • resolution (number, default: 5) - font size resolution to adjust to in percent

GitHub