tools: replace string concatenation with template

Replace string concatenation in tools/doc/type-parser.js
with template literals

PR-URL: https://github.com/nodejs/node/pull/15827
Reviewed-By: Ryan Graham <r.m.graham@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>

tools/doc/type-parser.js

@@ -1,8 +1,8 @@
 'use strict';
 const nodeDocUrl = '';
 const jsDocPrefix = 'https://developer.mozilla.org/en-US/docs/Web/JavaScript/';
-const jsDocUrl = jsDocPrefix + 'Reference/Global_Objects/';
-const jsPrimitiveUrl = jsDocPrefix + 'Data_structures';
+const jsDocUrl = `${jsDocPrefix}Reference/Global_Objects/`;
+const jsPrimitiveUrl = `${jsDocPrefix}Data_structures`;
 const jsPrimitives = {
   'boolean': 'Boolean',
   'integer': 'Number', // not a primitive, used for clarification
@@ -22,10 +22,10 @@ const jsGlobalTypes = [
   'AsyncFunction', 'SharedArrayBuffer'
 ];
 const typeMap = {
-  'Iterable': jsDocPrefix +
-              'Reference/Iteration_protocols#The_iterable_protocol',
-  'Iterator': jsDocPrefix +
-              'Reference/Iteration_protocols#The_iterator_protocol',
+  'Iterable':
+    `${jsDocPrefix}Reference/Iteration_protocols#The_iterable_protocol`,
+  'Iterator':
+    `${jsDocPrefix}Reference/Iteration_protocols#The_iterator_protocol`,
 
   'Buffer': 'buffer.html#buffer_class_buffer',
 
@@ -87,11 +87,10 @@ module.exports = {
         }
 
         if (typeUrl) {
-          typeLinks.push('<a href="' + typeUrl + '" class="type">&lt;' +
-            typeTextFull + '&gt;</a>');
+          typeLinks.push(`
+            <a href="${typeUrl}" class="type">&lt;${typeTextFull}&gt;</a>`);
         } else {
-          typeLinks.push('<span class="type">&lt;' + typeTextFull +
-                         '&gt;</span>');
+          typeLinks.push(`<span class="type">&lt;${typeTextFull}&gt;</span>`);
         }
       }
     });