Initial

resources/app/client/core/clipboard.js

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+/**
+ * A helper class to manage requesting clipboard permissions and provide common functionality for working with the
+ * clipboard.
+ */
+class ClipboardHelper {
+  constructor() {
+    if ( game.clipboard instanceof this.constructor ) {
+      throw new Error("You may not re-initialize the singleton ClipboardHelper. Use game.clipboard instead.");
+    }
+  }
+
+  /* -------------------------------------------- */
+
+  /**
+   * Copies plain text to the clipboard in a cross-browser compatible way.
+   * @param {string} text  The text to copy.
+   * @returns {Promise<void>}
+   */
+  async copyPlainText(text) {
+    // The clipboard-write permission name is not supported in Firefox.
+    try {
+      const result = await navigator.permissions.query({name: "clipboard-write"});
+      if ( ["granted", "prompt"].includes(result.state) ) {
+        return navigator.clipboard.writeText(text);
+      }
+    } catch(err) {}
+
+    // Fallback to deprecated execCommand here if writeText is not supported in this browser or security context.
+    document.addEventListener("copy", event => {
+      event.clipboardData.setData("text/plain", text);
+      event.preventDefault();
+    }, {once: true});
+    document.execCommand("copy");
+  }
+}