prefer const over let

Author: isaacs

functions/diff.js

@@ -7,12 +7,9 @@ const diff = (version1, version2) => {
   } else {
     const v1 = parse(version1)
     const v2 = parse(version2)
-    let prefix = ''
-    let defaultResult
-    if (v1.prerelease.length || v2.prerelease.length) {
-      prefix = 'pre'
-      defaultResult = 'prerelease'
-    }
+    const hasPre = v1.prerelease.length || v2.prerelease.length
+    const prefix = hasPre ? 'pre' : ''
+    const defaultResult = hasPre ? 'prerelease' : ''
     for (const key in v1) {
       if (key === 'major' || key === 'minor' || key === 'patch') {
         if (v1[key] !== v2[key]) {