text-zoom-event

text-zoom-resize

A library that will detect when a user zooms text in their browser. This is a common use case for people who are visually impaired.

Usage:

Initialize using textZoomEvent.init():

// It is better if you give this the value of 
// parseFloat(getComputedStyle(document.documentElement).fontSize
// when the doc is not zoomed.
textZoomEvent.init(16);

You can find the current zoom factor using textZoomEvent.resizeFactor():

console.log('on load, resize factor is ', textZoomEvent.resizeFactor());

You can also use the textzoom event to fire when the user zooms the text with their browser:

document.addEventListener('textzoom', function (e) {
    console.log('ds', textZoomEvent.unzoomPixelValue, e.detail.resizeFactor());
});

How can you test? Different browsers have different UIs for zooming text. Full details can be found on my blog post about this library at https://www.useragentman.com/blog/?p=7749