Added keys to tags in <Head> component #417

PierreRe · 2023-01-15T11:22:16Z

Added keys to to tags in Next.JS component to prevent duplication in rendered HTML when rewriting meta-tags in child components as best-practice approach.

Next.JS <Head> component is able to extend and replace meta information predefined in a higher component with information defined in child-components. Adding keys to the meta-, title- and link-tags prevents duplicate tag-rendering when overwriting information already set by a higher component. Added keys as best-practice.

vercel · 2023-01-15T11:22:19Z

@PierreRe is attempting to deploy a commit to the Chapter Three Team on Vercel.

A member of the Team first needs to authorize it.

JohnAlbin · 2023-10-22T07:15:10Z

From my understanding key is only needed for each item in an array. https://react.dev/learn/rendering-lists#keeping-list-items-in-order-with-key

Next.js's Head docs show using a key when Head is used multiple times on a single page: https://nextjs.org/docs/pages/api-reference/components/head

Can you explain why this change is needed? And the steps to reproduce?

PierreRe · 2023-10-22T17:29:40Z

Correct, the key property is only needed when Head is used multiple times.

Example

Head may be called in the most basic components/layout.tsx to set basic meta-information. layout.tsx is repsonsible for rendering the base layout of all pages in the starter example. A common use-case (for me), is to overwrite the meta-information on content-type level (i.e. component-level). This often results in basic pages having different attributes from taxonomy-term pages.
To prevent multiplication of those attributes, Head allows using said key attribute.

Using the Umami-Demo, pages/[...slug].tsx renders components/layout.tsx which then renders components/meta.tsx. Here, the meta:image attribute is provided. It is set to a static image.
As documented, a user may call Head again, later in the render process (for example in component/node--page.tsx) to set more attributes, or overwrite existing attributes. I observed that resetting the title attribute worked as expected. However trying to overwrite the og:image resulted in multiplication of the og:image-tag in the rendered HTML.

Reproduce

setting a fallback og:image in meta.tsx
setting more correct fallback-image to og:imge on components/node--page.tsx for nodes
(This should result in duplicate og_imge-tags)
rendering drupal-paragraphs within components/node--page.tsx
when rendering a paragraph with a custom flag (for example: "add as social-media image"), re-set og:image to it's final image via Head

Granted, steps 3 and 4 represent a worst-case scenario, however, step should be quite common.

Motivation

To give users a guideline on how to (correctly) set and overwrite Head attributes using next/head I proposed to add a namespaced key attribute.

JohnAlbin

I'm in the process of upgrading the codebase to Next.js v14 and the app router. However, we will create a new pages_starter that will still use the pages routing; I'll make sure it uses key on meta tags.

Migrating all the examples will take some time, so it will be useful in the interim to have keys in the examples.

Note: this PR fixes #416

JohnAlbin · 2023-12-05T12:59:58Z

examples/example-auth/pages/index.tsx

@@ -8,7 +8,7 @@ export default function IndexPage() {
  return (
    <>
      <Head>
-        <title>Next.js for Drupal | Authentication Example</title>
+        <title key="head_title">Next.js for Drupal | Authentication Example</title>


The Next.js docs at https://nextjs.org/docs/pages/api-reference/components/head mention that key should be added so that:

To avoid duplicate tags in your head you can use the key property, which will make sure the tag is only rendered once, as in the following example:

It then shows an example of a meta tag not being duplicated. I think "meta tag" is what they meant by "tag" rather than "html tag".

If Next.js is adding duplicate title tags to the markup, then that's a Next.js bug. I don't think adding key="head_title" to our codebase makes any sense.

JohnAlbin · 2023-12-05T13:02:28Z

examples/example-blog/components/meta.tsx

@@ -14,6 +14,7 @@ export function Meta({ title, tags }: MetaProps) {
  return (
    <Head>
      <link
+        key="head_link_canonical"


Let's not prefix our key's with head_ or even with link_ or meta_. It seems overly verbose. If React is trying to dedupe a link element, it doesn't need the extra specificity of a prefix that duplicates the HTML structure.

tldr; let's use key="canonical" here.

JohnAlbin · 2023-12-05T13:03:16Z

examples/example-blog/components/meta.tsx

          <meta
+            key="head_meta_description"


key="description" please.

…-in-meta-component

PierreRe · 2023-12-10T11:26:56Z

Cheers @JohnAlbin
You're right, adding a prefix is not necessary, as React dedupes on html elements. I updated this PR to the latest commit in the main branch and removed the unnecessary prefixes. I also went ahead and removed the prefixes on og:image and renamed the key to use underscores to be more in-line with the code-style.
Thanks for your input.

JohnAlbin

I don't think <title key="title"> is necessary.

JohnAlbin · 2023-12-11T10:02:53Z

examples/example-auth/pages/index.tsx

@@ -8,7 +8,7 @@ export default function IndexPage() {
  return (
    <>
      <Head>
-        <title>Next.js for Drupal | Authentication Example</title>
+        <title key="title">Next.js for Drupal | Authentication Example</title>


This code example is from the docs on Next.js that mention keys:

To avoid duplicate tags in your head you can use the key property, which will make sure the tag is only rendered once, as in the following example:

function IndexPage() { return ( <div> <Head> <title>My page title</title> <meta property="og:title" content="My page title" key="title" /> </Head> <Head> <meta property="og:title" content="My new title" key="title" /> </Head> <p>Hello world!</p> </div> ) }

You can see that don't put a key on the title tag.

Agreed, but not for the docs, but for the function behind deduplication of the <title> Tag in the actual Head component here: https://github.com/vercel/next.js/blob/c5b5b1e3a3d85d498770a974c250c864e8d2a761/packages/next/src/shared/lib/head.tsx#L84

As per the docs, we could argue that only a single <title> is declared and deduplication is therefore not strictly necessarry.
However, the actual NextJS <Head> component handles the <title> and <base> tag differently from the <meta> tag. I guess, my initial problem originates in line 106 of the head component which sets the isUnique variable to false if a meta-property is not "name" or has no key.
https://github.com/vercel/next.js/blob/c5b5b1e3a3d85d498770a974c250c864e8d2a761/packages/next/src/shared/lib/head.tsx#L106

It was an interesting dive into the head component,
Cheers

- Refactored the page title in several examples to follow a consistent format: "Next.js for Drupal | [Example Name]" - Removed unnecessary key attribute from the title element

PierreRe added 2 commits January 15, 2023 11:59

Added keys to tags in <Head> component

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JohnAlbin added need more info Maintainers need more info area: examples/* labels Oct 22, 2023

JohnAlbin removed the need more info Maintainers need more info label Dec 5, 2023

JohnAlbin requested changes Dec 5, 2023

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PierreRe added 4 commits December 10, 2023 12:10

Removed prefixes from keys in head components

cd7090a

Merge branch 'main' into feat/keyed_tags_in_meta_component

4577772

Refactored code as structured in main

50f9d78

Merge branch 'feat/keyed_tags_in_meta_component' into feat/keyed-tags…

78c1a5e

…-in-meta-component

JohnAlbin requested changes Dec 11, 2023

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PierreRe and others added 3 commits December 23, 2023 14:19

Merge branch 'main' into feat/keyed-tags-in-meta-component

b925171

Refactor page title in multiple examples

04f538e

- Refactored the page title in several examples to follow a consistent format: "Next.js for Drupal | [Example Name]" - Removed unnecessary key attribute from the title element

Merge branch 'main' into feat/keyed-tags-in-meta-component

cb6dfb2

JohnAlbin approved these changes Feb 22, 2024

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JohnAlbin merged commit 81b3830 into chapter-three:main Feb 22, 2024
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Added keys to tags in <Head> component #417

Added keys to tags in <Head> component #417

PierreRe commented Jan 15, 2023

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JohnAlbin commented Oct 22, 2023

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Added keys to tags in <Head> component #417

Added keys to tags in <Head> component #417

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PierreRe commented Jan 15, 2023

vercel bot commented Jan 15, 2023

JohnAlbin commented Oct 22, 2023

PierreRe commented Oct 22, 2023

Example

Reproduce

Motivation

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