Preloading Google Fonts

28
votes

Light House audit is suggesting that I preload key requests, specifically the two google fonts that I'm using in my React app. A Light House member suggested using: <link rel="preload" as="style" href="https://fonts.googleapis.com/css?family=Open+Sans|Roboto:700" crossorigin> <link rel="preconnect" href="https://fonts.gstatic.com/" crossorigin>

I know it's making the request because I see it in the waterfall and I get this console warning:

"The resource https://fonts.googleapis.com/css?family=Open+Sans|Roboto:700 was preloaded using link preload but not used within a few seconds from the window's load event. Please make sure it has an appropriate as value and it is preloaded intentionally."

Unfortunately the two font do not display in my app anymore. Do I need to define these in my CSS with @font-face or something like that?

2
javascripthtmlcssreactjslighthouse
I can't see your code, but I'd guess you replaced the <link rel="stylesheet"> with the <link rel="preload">. This is not sufficient. You'll need both, the preload and the stylesheet. – Loilo
So like this? <link rel="preload" as="style" rel="stylesheet" href="fonts.googleapis.com/css?family=Open+Sans|Roboto:700" crossorigin> – wildair
Not quite yet. You're not supposed to combine those tags into one but rather preserve both. You'll eventually end up with two <link> tags for each font. One for preload, one stylesheet. – Loilo
This works: <link rel="preconnect" href="fonts.gstatic.com" crossorigin> <link rel="preload" as="style" href="fonts.googleapis.com/css?family=Roboto:700" crossorigin> <link rel="preload" as="style" href="fonts.googleapis.com/css?family=Open+Sans" crossorigin> <link href="fonts.googleapis.com/css?family=Open+Sans" rel="stylesheet" crossorigin> <link href="fonts.googleapis.com/css?family=Roboto:700" rel="stylesheet" crossorigin> – wildair
Without adding the crossorgin property I get a render blocking stylesheet warning from LightHouse but, this whole endeavor to preload font fonts per Chrome's suggestion as upped my first meaningful paint to 3620ms from 2650ms and lower my lighthouse score from 88 to 79. – wildair

2 Answers

25
votes

The correct way to preload a font would be by adding both a preload link and a stylesheet. A simplified example, based on MDN is as follows:

<head>
  <meta charset="utf-8">
  <title>Preloading fonts</title>

  <link rel="preload" href="https://fonts.googleapis.com/css?family=Roboto&display=swap" as="style">
  <link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Roboto&display=swap">
</head>

<body>
</body>

In the above example, the preload link will send a request to fetch the font regardless of it being installed or not on the client and then use the stylesheet link to properly load and use it.

preload is more of a way to tell the browser that a resource will probably be needed, so that it will be requested regardless and then, if you need it or decide to use it, you can.

11
votes

It is recommended that you preconnect, then preload, and then finally load as follows:

<link rel='preconnect' href='https://fonts.gstatic.com' crossorigin>
<link rel='preload' as='style' href='https://fonts.googleapis.com/css2?family=Open+Sans|Roboto:wght@300&display=swap'>
<link rel='stylesheet' href='https://fonts.googleapis.com/css2?family=Open+Sans|Roboto:wght@700&display=swap'>

You cannot just preconnect and/or preload, you still need to load as usual. Then you just specify any font weight that is not the default for that given font by using :wght@700, for example. Between successive fonts you put the pipe | sign.