Add preferUnquoted option

Related-to: GH-12.

Author: wooorm

Diff for: index.d.ts

@@ -12,6 +12,11 @@ export {directiveFromMarkdown, directiveToMarkdown} from './lib/index.js'
  * Configuration.
  */
 export interface ToMarkdownOptions {
+  /**
+   * Leave attributes unquoted if that results in less bytes
+   * (default: `false`).
+   */
+  preferUnquoted?: boolean | null | undefined
   /**
    * Use the other quote if that results in less bytes
    * (default: `false`).

Diff for: lib/index.js

@@ -27,6 +27,7 @@ const own = {}.hasOwnProperty
 const emptyOptions = {}
 
 const shortcut = /^[^\t\n\r "#'.<=>`}]+$/
+const unquoted = /^[^\t\n\r "'<=>`}]+$/
 
 /**
  * Create an extension for `mdast-util-from-markdown` to enable directives in
@@ -89,6 +90,7 @@ export function directiveFromMarkdown() {
  */
 export function directiveToMarkdown(options) {
   const settings = options || emptyOptions
+
   if (
     settings.quote !== '"' &&
     settings.quote !== "'" &&
@@ -266,6 +268,10 @@ export function directiveToMarkdown(options) {
   function quoted(key, value, node, state) {
     if (!value) return key
 
+    if (settings.preferUnquoted && unquoted.test(value)) {
+      return key + '=' + value
+    }
+
     // If the alternative is less common than `quote`, switch.
     const preferred = settings.quote || state.options.quote || '"'
     const alternative = preferred === '"' ? "'" : '"'
@@ -282,10 +288,10 @@ export function directiveToMarkdown(options) {
 
     return (
       key +
-      ('=' +
-        appliedQuote +
-        stringifyEntitiesLight(value, {subset}) +
-        appliedQuote)
+      '=' +
+      appliedQuote +
+      stringifyEntitiesLight(value, {subset}) +
+      appliedQuote
     )
   }
 }

Diff for: readme.md

@@ -264,6 +264,9 @@ Configuration.
 
 ###### Parameters
 
+* `preferUnquoted`
+  (`boolean`, default: `false`)
+  — leave attributes unquoted if that results in less bytes
 * `quoteSmart`
   (`boolean`, default: `false`)
   — use the other quote if that results in less bytes