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40993e8ec7
- Use `let` instead of `var` throughout. All modern browsers support it
and have for many years, even the now-EOL IE11.[^ie]
- Add a `@ts-check` annotation so that anyone working on a TS-enabled
editor will get feedback inline about cases they may otherwise miss.
- Add JSDoc-based type definitions for the script, and fix some errors
that may occur at runtime. (These will be rare if they happen, but
getting rid of them is still a win!)
[^ie]: IE11 did not correctly support the semantics of `let` for `for`
loops, but the uses in the existing code here already used `var` in
a way which would trigger the same behavior as using `let` does.
101 lines
2.5 KiB
JavaScript
101 lines
2.5 KiB
JavaScript
// @ts-check
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/**
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* @typedef {{ attr: string, title: string }} FerrisType
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*/
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/** @type {Array<FerrisType>} */
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const FERRIS_TYPES = [
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{
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attr: 'does_not_compile',
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title: 'This code does not compile!'
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},
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{
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attr: 'panics',
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title: 'This code panics!'
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},
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{
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attr: 'not_desired_behavior',
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title: 'This code does not produce the desired behavior.'
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}
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]
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document.addEventListener('DOMContentLoaded', () => {
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for (let ferrisType of FERRIS_TYPES) {
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attachFerrises(ferrisType)
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}
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})
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/**
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* @param {FerrisType} type
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*/
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function attachFerrises(type) {
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let elements = document.getElementsByClassName(type.attr)
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for (let codeBlock of elements) {
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// Skip SVG etc.: in principle, these should never be attached to those, but
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// this means if someone happens to have a browser extension which *is*
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// attaching them, it will not break the code.
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if (!(codeBlock instanceof HTMLElement)) {
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continue
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}
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let lines = codeBlock.innerText.replace(/\n$/, '').split(/\n/).length
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/** @type {'small' | 'large'} */
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let size = lines < 4 ? 'small' : 'large'
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let container = prepareFerrisContainer(codeBlock, size == 'small')
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if (!container) {
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continue
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}
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container.appendChild(createFerris(type, size))
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}
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}
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/**
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* @param {HTMLElement} element - Code block element to attach a Ferris to.
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* @param {boolean} useButtons - Whether to attach to existing buttons.
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* @returns {Element | null} - The container element to use.
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*/
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function prepareFerrisContainer(element, useButtons) {
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let foundButtons = element.parentElement?.querySelector('.buttons')
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if (useButtons && foundButtons) {
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return foundButtons
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}
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let div = document.createElement('div')
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div.classList.add('ferris-container')
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if (!element.parentElement) {
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console.error(`Could not install Ferris on ${element}, which is missing a parent`);
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return null;
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}
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element.parentElement.insertBefore(div, element)
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return div
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}
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/**
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* @param {FerrisType} type
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* @param {'small' | 'large'} size
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* @returns {HTMLAnchorElement} - The generated anchor element.
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*/
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function createFerris(type, size) {
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let a = document.createElement('a')
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a.setAttribute('href', 'ch00-00-introduction.html#ferris')
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a.setAttribute('target', '_blank')
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let img = document.createElement('img')
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img.setAttribute('src', 'img/ferris/' + type.attr + '.svg')
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img.setAttribute('title', type.title)
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img.classList.add('ferris')
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img.classList.add('ferris-' + size)
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a.appendChild(img)
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return a
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}
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