Svelte Readotron

Svelte component to display an estimated reading time

---

Demo

:red_circle:  LIVE DEMO :red_circle:

Installation

yarn add @untemps/svelte-readotron

Usage

Basic usage

<script>
    import Readotron from '@untemps/svelte-readotron'
</script>

<main>
    <Readotron selector=".text" />
    <section class="text">...</section>
</main>

selector prop is mandatory as it points to which element contains the text content to parse. You can utilize any selector supported by the Web API querySelector function.
If several elements match the selector, it only parses the text of the first element in the array.

The component will wait for the element to be present in the DOM before parsing its content. If the element is not found after 1000ms, an error is raised and displayed.
This is achieved with the @untemps/dom-observer package.

Lang

'lang' is an optional prop that designates the language of the text to parse. The component implements the @untemps/read-per-minute underhand package which returns an estimation based on the lang (language).
Reading rates by lang come from "How many words do we read per minute? A review and meta-analysis of reading rate" by Marc Brysbaert - Department of Experimental Psychology Ghent University

Lang	Rate
default	200
ar	181
zh	260
nl	228
en	236
fi	195
fr	214
de	260
he	224
it	285
ko	226
es	278
sv	218

If a lang is not defined or the provided lang is not listed, the default value (200) will be applied.

Example

<script>
    import Readotron from '@untemps/svelte-readotron'
</script>

<main>
    <Readotron selector=".text" lang="en" />
    <section class="text">...</section>
</main>

Template

You can customize the Readotron display by using the template prop.

• A template can be a string with one or more tokens delimited with %

Example

<script>
    import Readotron from '@untemps/svelte-readotron'
</script>

<main>
    <Readotron selector=".text" template="Reading Time: %time% minutes (%words% words)" />
    <section class="text">...</section>
</main>

• A template can be a function with time and words as arguments.
  The function should return a template literal with the markup to display using optionally arguments as placeholders. But it may return any displayable type as well.

:warning: The string will be parsed with the {@html} expression: Be very careful with the content you pass or allow to pass in to this prop!

Example

<script>
    import Readotron from '@untemps/svelte-readotron'
</script>

<main>
    <Readotron selector=".text" template={(time, words) => `<Icon name='clock'> <strong>Reading Time: ${time} minutes</strong> (${words} words)`}/>
    <section class="text">
        ...
    </section>
</main>

Avalaible tokens/arguments

Token	Description
time	Estimated reading time (in minutes)
words	Number of words

Scroll Support

You are able to track and update component values by opting in the withScroll flag. This will change the time (remaining time to read) and words (number of remaining words) as the user scroll the document.

Note: There is no support for element scrolling so far, document only.

The component uses the scrollProgress underhand package to track document scrolling.

Example

<script>
    import Readotron from '@untemps/svelte-readotron'
</script>

<main>
    <Readotron selector=".text" withScroll />
    <section class="text">...</section>
</main>

Change Event

If you need to be notified whenever values change, you may attach a listener to the change event emitted by the component.

---

Note: The change event will be dispatched only if the withScroll prop is set to true since this is the only use case that triggers the change event so far

---

The handler will be triggered for the first time during the mounting phase with the initial values.

Handler Signature

Here are the properties available inside the event.detail sent with the event:

Props	Type	Description
time	number	Estimated remaining reading time (in minutes)
words	number	Number of remaining words
progress	number	Ratio of progression (between 0 and 1)

Example

<script>
    import Readotron from '@untemps/svelte-readotron'
</script>

<main>
    <Readotron selector=".text" withScroll on:change={(event) => {
        const {detail: {time, words, progress}} = event
        console.log('Time:', time + ' minutes')
        console.log('Words:', words + ' remaining words')
        console.log('Progress:', progress * 100 + '%')
    }}/>
    <section class="text">
        ...
    </section>
</main>

Recipe

The event dispatching allows to animate a progress bar in sync with the reading status:

<script>
    import Readotron from '@untemps/svelte-readotron'

    let readingProgress = 0
</script>

<main>
    <Readotron selector=".text" withScroll on:change={(event) => {
        readingProgress = event.detail.progress
    }}/>
    <section class="text">
        ...
    </section>
    <div class="progress-bar" style="width: {readingProgress * 100}%"></div>
</main>

<style>
    .progress-bar {
        background-color: #0075ff;
        height: 20px;
        position: fixed;
        left: 0;
        bottom: 0;
    }
</style>

Slot

Another way to customize the display is to use the <slot> element.
If a <slot> is passed in as Readotron child and correctly set (see Constraints below), it will be rendered instead of the default layout. This has precedence over the template prop.
This allows to set a specific tag as parent if needed.

Constraints:

The <slot> element has to be set with the prop slot="content"

Avalaible tokens

Like template, tokens are passed back to the component to display dynamic values (see Svelte API documentation):

Token	Description
time	Estimated reading time (in minutes)
words	Number of words

Example

<script>
    import Readotron from '@untemps/svelte-readotron'
</script>

<main>
    <Readotron selector=".text">
        <span slot="content" let:time let:words>{time} min ({words} words)</span>
    </Readotron>
    <section class="text">...</section>
</main>

Please see the Svelte API documentation to know more about the <slot> element.

Styles

All HTML attributes are automatically passed to the parent element of the component (span).
That means you can query the class attribute to customize the style of the component.

Example

<script>
    import Readotron from '@untemps/svelte-readotron'
</script>

<main>
    <Readotron selector=".text" class="readotron" />
    <section class="text">...</section>
</main>

<style>
    .readotron {
        color: #0075ff;
        font-weight: 600;
    }
</style>

If you use a <slot> element, as it will replace the original layout, you have to switch the class name from the <Readotron> element to the <slot> element.

<script>
    import Readotron from '@untemps/svelte-readotron'
</script>

<main>
    <Readotron selector=".text">
        <span class="readotron" slot="content" let:time>{time} min</span>
    </Readotron>
    <section class="text">...</section>
</main>

Error

If an error occurs during the parsing phase, the component catches and exposes it through an error variable which is displayed as is it by default. That means the error message uses the exact same styles as time value.

You may want to customize this error message, so the component provides a slot, named error, which replaces the default display if passed in.

Example

<script>
    import Readotron from '@untemps/svelte-readotron'
</script>

<main>
    <Readotron selector=".text">
        <span class="readotron" slot="content" let:time>{time} min</span>
        <span class="error" slot="error" let:error>Oops!</span>
    </Readotron>
    <section class="text">...</section>
</main>

<style>
    .readotron {
        color: #0075ff;
        font-weight: 600;
    }

    .error {
        color: #ff0000;
        font-weight: 600;
    }
</style>

Constraints:

The <slot> element has to be set with the prop slot="error"

Avalaible tokens

Error message is passed back to the component for display purpose if needed (see Svelte API documentation):

Token	Description
error	Original error message

API

Props	Type	Default	Description
selector	string	(required)	Selector of the element which contains the content to parse. See document.querySelector
lang	string	'en'	Lang of the content [""ar', 'zh', 'nl', 'en', 'fi', 'fr', 'de', 'he', 'it', 'ko', 'es', 'sv']
template	string or function	'%time% min read'	Display template which contains dynamic tokens to be replaced by the parsed values. See Template
withScroll	boolean	false	Enable updates on scroll. If true, time and words values will reflect the document scroll position

Events

Props	Arguments	Type	Description
change			Dispatches whenever time and words have changed
	time	number	Estimated remaining reading time (in minutes) Estimated remaining reading time (in minutes)
	words	number	Number of remaining words
	progress	number	Ratio of progression (between 0 and 1)

Development

The component can be served for development purpose on http://localhost:10001/ running:

yarn dev

Contributing

Contributions are warmly welcomed:

• Fork the repository
• Create a feature branch
• Develop the feature AND write the tests (or write the tests AND develop the feature)
• Commit your changes using Angular Git Commit Guidelines
• Submit a Pull Request