Refactor to improve bundle size

Author: wooorm

index.js

@@ -4,19 +4,12 @@ var visit = require('unist-util-visit')
 
 module.exports = shiftHeading
 
-var floor = Math.floor
-var min = 1
-var max = 6
-
-// Character codes.
-var digit0 = 48
-
 function shiftHeading(tree, shift) {
   if (
     typeof shift !== 'number' ||
     !shift ||
     !isFinite(shift) ||
-    floor(shift) !== shift
+    Math.floor(shift) !== shift
   ) {
     throw new Error('Expected a non-null finite integer, not `' + shift + '`')
   }
@@ -37,8 +30,8 @@ function shiftHeading(tree, shift) {
       name === 'h5' ||
       name === 'h6'
     ) {
-      rank = name.charCodeAt(1) - digit0 + shift
-      node.tagName = 'h' + (rank > max ? max : rank < min ? min : rank)
+      rank = name.charCodeAt(1) - 48 /* `0` */ + shift
+      node.tagName = 'h' + (rank > 6 ? 6 : rank < 1 ? 1 : rank)
     }
   }
 }