110 lines
3.9 KiB
JavaScript
110 lines
3.9 KiB
JavaScript
// import { sendEvent } from './events'
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import Cookies from 'js-cookie'
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// Determines whether images are hidden or displayed on first visit.
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const hideImagesByDefault = false
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// Set the image placeholder icon here.
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const placeholderImagePath = '/assets/images/octicons/image.svg'
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/*
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* This module adds a new icon button in the margin to toggle all images on the page.
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* It uses cookies to keep track of a user's selected image preference.
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*/
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export default function () {
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const toggleImagesBtn = document.getElementById('js-toggle-images')
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if (!toggleImagesBtn) return
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// If there are no images on the page, return!
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// Don't include images in tables, which are already small and shouldn't be hidden.
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const images = [...document.querySelectorAll('img')].filter(img => !img.closest('table'))
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if (!images.length) return
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// The button is hidden by default so it doesn't appear on browsers with JS disabled.
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// If there are images on a docs page and JS is enabled, display the toggle button.
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toggleImagesBtn.removeAttribute('hidden')
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// Look for a cookie with image visibility preference; otherwise, use the default.
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const hideImagesPreferred = (Cookies.get('hideImagesPreferred') === 'true') || hideImagesByDefault
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// Hide the images if that is the preference.
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if (hideImagesPreferred) {
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toggleImages(images, 'hide')
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}
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// Get the span elements containing the off and on icons.
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const offIcon = document.getElementById('js-off-icon')
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const onIcon = document.getElementById('js-on-icon')
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// Get the aria-labels from the span elements for the tooltips.
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const tooltipImagesOff = offIcon.getAttribute('aria-label')
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const tooltipImagesOn = onIcon.getAttribute('aria-label')
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// Set the starting state depending on user preferences.
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if (hideImagesPreferred) {
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offIcon.removeAttribute('hidden')
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toggleImagesBtn.setAttribute('aria-label', tooltipImagesOff)
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} else {
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onIcon.removeAttribute('hidden')
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toggleImagesBtn.setAttribute('aria-label', tooltipImagesOn)
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}
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// If images are hidden by default, showOnNextClick should be false.
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// If images are not hidden by default, showOnNextClick should be true.
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let showOnNextClick = !hideImagesPreferred
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toggleImagesBtn.addEventListener('click', (e) => {
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if (showOnNextClick) {
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// Button should say "Images are off" on first click (depending on prefs)
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offIcon.removeAttribute('hidden')
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onIcon.setAttribute('hidden', true)
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toggleImagesBtn.setAttribute('aria-label', tooltipImagesOff)
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toggleImages(images, 'hide')
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} else {
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// Button should say "Images are on" on another click
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offIcon.setAttribute('hidden', true)
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onIcon.removeAttribute('hidden')
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toggleImagesBtn.setAttribute('aria-label', tooltipImagesOn)
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toggleImages(images, 'show')
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}
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// Remove focus from the button after click so the tooltip does not stay displayed.
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toggleImagesBtn.blur()
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// Save this preference as a cookie.
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Cookies.set('hideImagesPreferred', showOnNextClick)
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// Toggle the action on every click.
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showOnNextClick = !showOnNextClick
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// TODO Track image toggle events
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// sendEvent({ type: 'imageToggle' })
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})
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}
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function toggleImages (images, action) {
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for (const img of images) {
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toggleImage(img, action)
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}
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}
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function toggleImage (img, action) {
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const parentEl = img.parentNode
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// Style the parent element and image depending on the state.
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if (action === 'show') {
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img.src = img.getAttribute('originalSrc')
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img.style.border = '2px solid var(--color-auto-gray-2)'
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parentEl.style.display = 'block'
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parentEl.style['margin-top'] = '20px'
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parentEl.style.padding = '10px 0'
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} else {
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if (!img.getAttribute('originalSrc')) img.setAttribute('originalSrc', img.src)
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img.src = placeholderImagePath
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img.style.border = 'none'
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parentEl.style.display = 'inline'
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parentEl.style['margin-top'] = '0'
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parentEl.style.padding = '1px 6px'
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}
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}
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