avoid many property lookups with some local caches (#315)

Author: bartveneman

src/index.js

@@ -281,10 +281,13 @@ function analyze(css) {
           break
         }
 
-        if (endsWith('\\9', node.unit)) {
-          units.push(node.unit.substring(0, node.unit.length - 2), this.declaration.property)
+        /** @type {string} */
+        let unit = node.unit
+
+        if (endsWith('\\9', unit)) {
+          units.push(unit.substring(0, unit.length - 2), this.declaration.property)
         } else {
-          units.push(node.unit, this.declaration.property)
+          units.push(unit, this.declaration.property)
         }
 
         return this.skip
@@ -400,6 +403,8 @@ function analyze(css) {
         }
 
         walk(node, function (valueNode) {
+          let nodeName = valueNode.name
+
           switch (valueNode.type) {
             case 'Hash': {
               let hexLength = valueNode.value.length
@@ -412,15 +417,14 @@ function analyze(css) {
               return this.skip
             }
             case 'Identifier': {
-              let { name } = valueNode
               // Bail out if it can't be a color name
               // 20 === 'lightgoldenrodyellow'.length
               // 3 === 'red'.length
-              if (name.length > 20 || name.length < 3) {
+              if (nodeName.length > 20 || nodeName.length < 3) {
                 return this.skip
               }
               let stringified = stringifyNode(valueNode)
-              let lowerCased = name.toLowerCase()
+              let lowerCased = nodeName.toLowerCase()
 
               if (namedColors.has(lowerCased)) {
                 colors.push(stringified, property)
@@ -436,10 +440,10 @@ function analyze(css) {
             }
             case 'Function': {
               // Don't walk var() multiple times
-              if (strEquals('var', valueNode.name)) {
+              if (strEquals('var', nodeName)) {
                 return this.skip
               }
-              let fnName = valueNode.name.toLowerCase()
+              let fnName = nodeName.toLowerCase()
               let stringified = stringifyNode(valueNode)
               if (colorFunctions.has(fnName)) {
                 colors.push(stringified, property)

src/string-utils.js

@@ -58,14 +58,14 @@ export function endsWith(base, test) {
 /**
  * Case-insensitive testing whether a string starts with a given substring
  * @param {string} base
- * @param {test} test
+ * @param {string} test
  * @returns {boolean} true if `test` starts with `base`, false otherwise
  */
 export function startsWith(base, test) {
   let len = base.length
   if (test.length < len) return false
 
-  for (let i = 0; i < base.length; i++) {
+  for (let i = 0; i < len; i++) {
     if (compareChar(base.charCodeAt(i), test.charCodeAt(i)) === false) {
       return false
     }