reduce complexity of zest.js parseSelector

Author: bkdotcom

src/Debug/js/zest.js

@@ -46,7 +46,6 @@ var zest = (function () {
   // parse/split selector into chunks
   // chunks contains any custom pseudo-selectors at the end of the chunk
   function parseSelector (selector) {
-
     // Replace string-based pseudo-selectors in the selector
     Object.entries(pseudoSelectors).forEach(([name, mixed]) => {
       if (typeof mixed === 'string') {
@@ -60,45 +59,48 @@ var zest = (function () {
     // Rejoin parts such that parts end with custom pseudo-selectors
     const rejoinedParts = [];
     for (let i = 0; i < parts.length; i++) {
-      if (i > 0 && /^[>+~]$/.test(parts[i])) {
-        const combined = parts[i] + ' ' + parts[i + 1];
-        containsCustomPseudoSelectors(rejoinedParts[rejoinedParts.length - 1]) === false
-          ? rejoinedParts[rejoinedParts.length - 1] += ' ' + combined
-          : rejoinedParts.push(combined);
-        i++;  // Skip the next part as it has been joined
-      } else {
+      if (i < 1 || /^[>+~]$/.test(parts[i]) === false) {
         rejoinedParts.push(parts[i]);
+        continue
       }
-    }
-
-    return rejoinedParts.map(part => {
-      const parts = part.split(REGEX_PSEUDO_SELECTORS);
-      const customPseudoSelectors = Object.keys(pseudoSelectors);
-      var baseSelector = parts.shift();
-      var pseudosCustom = [];
-      var pseudosStandard = [];
-      for (const part of parts) {
-        customPseudoSelectors.includes(part)
-          ? pseudosCustom.push(part)
-          : pseudosStandard.push(part);
-        }
-      if (pseudosStandard.length > 0) {
-        // Add standard pseudo-selectors to the baseSelector
-        baseSelector += pseudosStandard.map(p => `:${p}`).join('');
-      } else if (baseSelector && /[>+~]\s*$/.test(baseSelector)) {
-        // baseSelector ends with a CSS combinator -> append "*"
-        baseSelector += ' *';
-      } else if (baseSelector && /^\s*[>+~]/.test(baseSelector)) {
-        // baseSelector starts with a CSS combinator -> prepend ":scope"
-        baseSelector = ':scope ' + baseSelector;
-      } else if (baseSelector === '') {
-        baseSelector = '*';
-      }
-      return {
-        baseSelector: baseSelector.trim(),
-        pseudoParts: pseudosCustom,
+      const combined = parts[i] + ' ' + parts[i + 1];
+      containsCustomPseudoSelectors(rejoinedParts[rejoinedParts.length - 1]) === false
+        ? rejoinedParts[rejoinedParts.length - 1] += ' ' + combined
+        : rejoinedParts.push(combined);
+      i++;  // Skip the next part as it has been joined
+    }
+
+    return rejoinedParts.map(partMap)
+  }
+
+  // For a given part, separate base selector and custom pseudo-selectors
+  function partMap (part) {
+    const parts = part.split(REGEX_PSEUDO_SELECTORS);
+    const customPseudoSelectors = Object.keys(pseudoSelectors);
+    var baseSelector = parts.shift();
+    var pseudosCustom = [];
+    var pseudosStandard = [];
+    for (const part of parts) {
+      customPseudoSelectors.includes(part)
+        ? pseudosCustom.push(part)
+        : pseudosStandard.push(part);
       }
-    })
+    if (pseudosStandard.length > 0) {
+      // Add standard pseudo-selectors to the baseSelector
+      baseSelector += pseudosStandard.map(p => `:${p}`).join('');
+    } else if (baseSelector && /[>+~]\s*$/.test(baseSelector)) {
+      // baseSelector ends with a CSS combinator -> append "*"
+      baseSelector += ' *';
+    } else if (baseSelector && /^\s*[>+~]/.test(baseSelector)) {
+      // baseSelector starts with a CSS combinator -> prepend ":scope"
+      baseSelector = ':scope ' + baseSelector;
+    } else if (baseSelector === '') {
+      baseSelector = '*';
+    }
+    return {
+      baseSelector: baseSelector.trim(),
+      pseudoParts: pseudosCustom,
+    }
   }
 
   // for the given element, perform a query or match