perf: avoid deoptimization on out of bounds (#4)

lib/parse.js

@@ -30,13 +30,14 @@ function parse(input) {
   let equalityIndex = -1;
   let shouldDecode = false;
   let hasPlus = false;
+  const lastIndex = input.length;
 
   // Have a boundary of input.length + 1 to access last pair inside the loop.
-  for (let i = 0; i < input.length + 1; i++) {
-    let c = input.charCodeAt(i);
+  for (let i = 0; i < lastIndex + 1; i++) {
+    let c = (i !== lastIndex && input.charCodeAt(i)) || 0;
 
     // Handle '&' and end of line to pass the current values to result
-    if (c === 38 || isNaN(c)) {
+    if (c === 38 || c === 0) {
       // Check if the current range consist of a single key
       if (equalityIndex <= startingIndex) {
         key = input.slice(startingIndex + 1, i);