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BezierInfo-2/lib/site/social-updater.js
2020-08-03 18:27:33 -07:00

81 lines
2.4 KiB
JavaScript

/**
* This file is responsible for making sure that the reddit, hn, twitter, etc. linkouts
* are updated to reflect the section someone is reading, rather than always pointing to
* base article itself.
*/
(function tryToBind() {
if (!document.querySelector(`map[name="rhtimap"]`)) {
return setTimeout(tryToBind, 300);
}
class Tracker {
constructor() {
this.section = false;
this.hash = false;
this.socials = ["rdt","hn","twt"];
}
update(data) {
this.section = data.section;
this.hash = data.hash;
this.socials.forEach(social => {
var area = document.querySelector(`map area.sclnk-${social}`);
area.href = this[`get_${social}`]();
});
}
get url() {
return encodeURIComponent(`https://pomax.github.io/bezierinfo${this.hash ? this.hash : ''}`);
}
getTitle() {
var title = `A Primer on Bézier Curves`;
if (this.section) {
title = `${this.section}-${title}`;
}
return encodeURIComponent(title);
}
get_rdt() {
var title = this.getTitle();
var text = encodeURIComponent(`A free, online book for when you really need to know how to do Bézier things.`);
return `https://www.reddit.com/submit?url=${this.url}&title=${title}&text=${text}`;
}
get_hn() {
var title = this.getTitle();
return `https://news.ycombinator.com/submitlink?u=${this.url}&t=${title}`;
}
get_twt() {
var text = encodeURIComponent(`Reading "${this.section}" by @TheRealPomax over on `) + this.url;
return `https://twitter.com/intent/tweet?original_referer=${this.url}&text=${text}&hashtags=bezier,curves,maths`;
}
};
// we set the section and fragmentid based on which ever section's heading is nearest
// the top of the screen, either just off-screen or in-screen
var tracker = new Tracker();
var anchors = Array.from(document.querySelectorAll("section h2 a"));
var sections = anchors.map(a => a.parentNode);
var sectionData = sections.map(section => {
return {
section: section.textContent,
hash: section.querySelector("a").hash
};
});
window.addEventListener("scroll", function(evt) {
var min = 99999999999999999;
var element = false;
sections.forEach( (s,pos) => {
var v = Math.abs(s.getBoundingClientRect().top);
if (v < min) { min = v; element = pos; }
});
tracker.update(sectionData[element]);
}, { passive: true });
}());