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Merged
merged 6 commits into from
Oct 29, 2020
Merged

Add documentation for $$slots #5277

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f20d955
site: add documentation for $$slots
CMessinides Aug 15, 2020
54527f0
site: revise $$slots tutorial chapter
CMessinides Aug 18, 2020
9a27617
docs: clarify omitted slot vs empty slot in $$slots
CMessinides Sep 30, 2020
c2217ee
Merge branch 'master' into pr/5277
Conduitry Oct 29, 2020
8b8271b
slightly rearrange $$slots section in API docs
Conduitry Oct 29, 2020
be85397
rename tutorial 'Checking slots' -> 'Checking for slot content'
Conduitry Oct 29, 2020
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25 changes: 25 additions & 0 deletions site/content/docs/02-template-syntax.md
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Expand Up @@ -1317,6 +1317,31 @@ Named slots allow consumers to target specific areas. They can also have fallbac
</div>
```

#### [`$$slots`](slots_object)

---

`$$slots` is an object whose keys are the names of the slots passed into the component by the parent. If the parent does not pass in a slot with a particular name, that name will not be a present in `$$slots`. This allows components to render a slot (and other elements, like wrappers for styling) only if the parent provides it.

Note that explicitly passing in an empty named slot will add that slot's name to `$$slots`. For example, if a parent passes `<div slot="title" />` to a child component, `$$slots.title` will be truthy within the child.

```sv
<!-- App.svelte -->
<Card>
<h1 slot="title">Blog Post Title</h1>
</Card>

<!-- Card.svelte -->
<div>
<slot name="title"></slot>
{#if $$slots.description}
<!-- This slot and the <hr> before it will not render. -->
<hr>
<slot name="description"></slot>
{/if}
</div>
```

#### [`<slot let:`*name*`={`*value*`}>`](slot_let)

---
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57 changes: 57 additions & 0 deletions site/content/tutorial/14-composition/04-optional-slots/app-a/App.svelte
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@@ -0,0 +1,57 @@
<script>
import Project from './Project.svelte'
import Comment from './Comment.svelte'
</script>

<style>
h1 {
font-weight: 300;
margin: 0 1rem;
}

ul {
list-style: none;
padding: 0;
margin: 0.5rem;
display: flex;
}

@media (max-width: 600px) {
ul {
flex-direction: column;
}
}

li {
padding: 0.5rem;
flex: 1 1 50%;
min-width: 200px;
}
</style>

<h1>
Projects
</h1>

<ul>
<li>
<Project
title="Add Typescript support"
tasksCompleted={25}
totalTasks={57}
>
<div slot="comments">
<Comment name="Ecma Script" postedAt={new Date('2020-08-17T14:12:23')}>
<p>Those interface tests are now passing.</p>
</Comment>
</div>
</Project>
</li>
<li>
<Project
title="Update documentation"
tasksCompleted={18}
totalTasks={21}
/>
</li>
</ul>
56 changes: 56 additions & 0 deletions site/content/tutorial/14-composition/04-optional-slots/app-a/Comment.svelte
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@@ -0,0 +1,56 @@
<script>
export let name;
export let postedAt;

$: avatar = `https://ui-avatars.com/api/?name=${name.replace(/ /g, '+')}&rounded=true&background=ff3e00&color=fff&bold=true`;
</script>

<style>
article {
background-color: #fff;
border: 1px #ccc solid;
border-radius: 4px;
padding: 1rem;
}

.header {
align-items: center;
display: flex;
}

.details {
flex: 1 1 auto;
margin-left: 0.5rem
}

h4 {
margin: 0;
}

time {
color: #777;
font-size: 0.75rem;
text-decoration: underline;
}

.body {
margin-top: 0.5rem;
}

.body :global(p) {
margin: 0;
}
</style>

<article>
<div class="header">
<img src={avatar} alt="" height="32" width="32">
<div class="details">
<h4>{name}</h4>
<time datetime={postedAt.toISOString()}>{postedAt.toLocaleDateString()}</time>
</div>
</div>
<div class="body">
<slot></slot>
</div>
</article>
62 changes: 62 additions & 0 deletions site/content/tutorial/14-composition/04-optional-slots/app-a/Project.svelte
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@@ -0,0 +1,62 @@
<script>
export let title;
export let tasksCompleted = 0;
export let totalTasks = 0;
</script>

<style>
article {
border: 1px #ccc solid;
border-radius: 4px;
position: relative;
}

article > div {
padding: 1.25rem;
}

article.has-discussion::after {
content: '';
background-color: #ff3e00;
border-radius: 10px;
box-shadow: 0 2px 4px rgba(0,0,0,0.2);
height: 20px;
position: absolute;
right: -10px;
top: -10px;
width: 20px;
}

h2,
h3 {
margin: 0 0 0.5rem;
}

h3 {
font-size: 0.875rem;
font-weight: 500;
letter-spacing: 0.08em;
text-transform: uppercase;
}

p {
color: #777;
margin: 0;
}

.discussion {
background-color: #eee;
border-top: 1px #ccc solid;
}
</style>

<article class:has-discussion={true}>
<div>
<h2>{title}</h2>
<p>{tasksCompleted}/{totalTasks} tasks completed</p>
</div>
<div class="discussion">
<h3>Comments</h3>
<slot name="comments"></slot>
</div>
</article>
57 changes: 57 additions & 0 deletions site/content/tutorial/14-composition/04-optional-slots/app-b/App.svelte
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Original file line number Diff line number Diff line change
@@ -0,0 +1,57 @@
<script>
import Project from './Project.svelte'
import Comment from './Comment.svelte'
</script>

<style>
h1 {
font-weight: 300;
margin: 0 1rem;
}

ul {
list-style: none;
padding: 0;
margin: 0.5rem;
display: flex;
}

@media (max-width: 600px) {
ul {
flex-direction: column;
}
}

li {
padding: 0.5rem;
flex: 1 1 50%;
min-width: 200px;
}
</style>

<h1>
Projects
</h1>

<ul>
<li>
<Project
title="Add Typescript support"
tasksCompleted={25}
totalTasks={57}
>
<div slot="comments">
<Comment name="Ecma Script" postedAt={new Date('2020-08-17T14:12:23')}>
<p>Those interface tests are now passing.</p>
</Comment>
</div>
</Project>
</li>
<li>
<Project
title="Update documentation"
tasksCompleted={18}
totalTasks={21}
/>
</li>
</ul>
56 changes: 56 additions & 0 deletions site/content/tutorial/14-composition/04-optional-slots/app-b/Comment.svelte
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Original file line number Diff line number Diff line change
@@ -0,0 +1,56 @@
<script>
export let name;
export let postedAt;

$: avatar = `https://ui-avatars.com/api/?name=${name.replace(/ /g, '+')}&rounded=true&background=ff3e00&color=fff&bold=true`;
</script>

<style>
article {
background-color: #fff;
border: 1px #ccc solid;
border-radius: 4px;
padding: 1rem;
}

.header {
align-items: center;
display: flex;
}

.details {
flex: 1 1 auto;
margin-left: 0.5rem
}

h4 {
margin: 0;
}

time {
color: #777;
font-size: 0.75rem;
text-decoration: underline;
}

.body {
margin-top: 0.5rem;
}

.body :global(p) {
margin: 0;
}
</style>

<article>
<div class="header">
<img src={avatar} alt="" height="32" width="32">
<div class="details">
<h4>{name}</h4>
<time datetime={postedAt.toISOString()}>{postedAt.toLocaleDateString()}</time>
</div>
</div>
<div class="body">
<slot></slot>
</div>
</article>
64 changes: 64 additions & 0 deletions site/content/tutorial/14-composition/04-optional-slots/app-b/Project.svelte
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Original file line number Diff line number Diff line change
@@ -0,0 +1,64 @@
<script>
export let title;
export let tasksCompleted = 0;
export let totalTasks = 0;
</script>

<style>
article {
border: 1px #ccc solid;
border-radius: 4px;
position: relative;
}

article > div {
padding: 1.25rem;
}

article.has-discussion::after {
content: '';
background-color: #ff3e00;
border-radius: 10px;
box-shadow: 0 2px 4px rgba(0,0,0,0.2);
height: 20px;
position: absolute;
right: -10px;
top: -10px;
width: 20px;
}

h2,
h3 {
margin: 0 0 0.5rem;
}

h3 {
font-size: 0.875rem;
font-weight: 500;
letter-spacing: 0.08em;
text-transform: uppercase;
}

p {
color: #777;
margin: 0;
}

.discussion {
background-color: #eee;
border-top: 1px #ccc solid;
}
</style>

<article class:has-discussion={$$slots.comments}>
<div>
<h2>{title}</h2>
<p>{tasksCompleted}/{totalTasks} tasks completed</p>
</div>
{#if $$slots.comments}
<div class="discussion">
<h3>Comments</h3>
<slot name="comments"></slot>
</div>
{/if}
</article>
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