Adds new rule htmlacademy/req-mailto

Author: nikolai-shabalin

rules/req-mailto/index.js

@@ -0,0 +1,30 @@
+'use strict';
+const { has_non_empty_attribute, is_tag_node, attribute_value } = require('@linthtml/dom-utils');
+
+const emailRegex = /[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}/;
+const isNotEmptyLink = (node) => node.childNodes.length > 0;
+const isEmailContent = (node) => emailRegex.test(node.childNodes[0].data);
+const reportError = (node) => ({
+  position: node.loc,
+  message: 'The href attribute of the <a> tag must start with "mailto:" if it contains an email'
+});
+
+module.exports = {
+  name: 'htmlacademy/req-mailto',
+  // eslint-disable-next-line camelcase
+  lint(node, rule_config, { report }) {
+    if (is_tag_node(node) && node.name === 'a') {
+      if (isNotEmptyLink(node) && isEmailContent(node)) {
+        if (has_non_empty_attribute(node, 'href')) {
+          const hrefValue = attribute_value(node, 'href').chars;
+
+          if (!hrefValue.startsWith('mailto:')) {
+            report(reportError(node));
+          }
+        } else {
+          report(reportError(node));
+        }
+      }
+    }
+  }
+};