move stuff to src folder, clarify readme

src/lodestone.mjs

@@ -0,0 +1,32 @@
+// Utilities for scraping data from the Lodestone
+
+/**
+ * @see https://stackoverflow.com/a/6969486
+ * @param {string}
+ * @returns {string}
+ */
+const regExpEscape = str => str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
+
+/**
+ * Creates a regular expression that matches a link to the named item and
+ * captures its EDB ID from the matched link's `href` attribute.
+ * @param {string} name
+ * @returns {RegExp}
+ */
+const itemLinkRegExp = name => new RegExp(`<a href="/lodestone/playguide/db/item/(?<id>[a-z0-9]+)[^"]+"[^>]*>(?<name>${regExpEscape(name)})</a>`, 'i');
+
+/**
+ * Gets the ID of the named item in Eorzea Database.
+ * @param {string} name
+ * @returns {Promise<string | undefined>}
+ */
+export async function findItemEDBID (name) {
+	// execute a search for the item's name
+	const searchURL = `https://na.finalfantasyxiv.com/lodestone/playguide/db/item/?q=${encodeURIComponent(name)}`;
+	const response = await fetch(searchURL);
+	const body = await response.text();
+	// find an `<a>` in the HTML response whose text exactly matches the name
+	const match = body.match(itemLinkRegExp(name));
+	// return the ID parsed from the URL in the `href` attribute
+	return match?.groups.id;
+}