Remove boolean support from options.target

Now that there is no default anymore, a boolean of `true` no longer makes
sense, and `false` is equivalent to `null` or `undefined`.
Use `null` or `undefined` instead.

index.js

@@ -5,7 +5,7 @@
  *
  * @typedef {Element['children'][number]} ElementChild
  *
- * @typedef {'_self'|'_blank'|'_parent'|'_top'|false} Target
+ * @typedef {'_self'|'_blank'|'_parent'|'_top'} Target
  * @typedef {Array<string>|string|false} Rel
  * @typedef {Array<string>} Protocols
  * @typedef {ElementChild|Array<ElementChild>} Content
@@ -33,10 +33,10 @@
  *
  * @typedef Options
  *   Configuration.
- * @property {Target|TargetCallback} [target='_blank']
+ * @property {Target|TargetCallback} [target]
  *   How to display referenced documents (`string?`: `_self`, `_blank`,
  *   `_parent`, or `_top`, default: `_blank`).
- *   Pass `false` to not set `target`s on links.
+ *   The default (nothing) is to not set `target`s on links.
  * @property {Rel|RelCallback} [rel=['nofollow', 'noopener', 'noreferrer']]
  *   Link types to hint about the referenced documents.
  *   Pass `false` to not set `rel`s on links.
@@ -60,7 +60,6 @@ import {parse} from 'space-separated-tokens'
 import absolute from 'is-absolute-url'
 import extend from 'extend'
 
-const defaultTarget = false
 const defaultRel = ['nofollow']
 const defaultProtocols = ['http', 'https']
 
@@ -109,8 +108,8 @@ export default function rehypeExternalLinks(options = {}) {
           callIfNeeded(options.contentProperties, node) || {}
 
         if (absolute(url) && protocols.includes(protocol)) {
-          if (target !== false) {
-            node.properties.target = target || defaultTarget
+          if (target) {
+            node.properties.target = target
           }
 
           if (rel !== false) {

readme.md

@@ -86,7 +86,7 @@ import rehypeStringify from 'rehype-stringify'
 const file = await unified()
   .use(remarkParse)
   .use(remarkRehype)
-  .use(rehypeExternalLinks, {target: false, rel: ['nofollow']})
+  .use(rehypeExternalLinks, {rel: ['nofollow']})
   .use(rehypeStringify)
   .process('[rehype](https://github.com/rehypejs/rehype)')
 
@@ -115,12 +115,12 @@ Configuration (optional).
 ###### `options.target`
 
 How to open external documents (`string?`: `_self`, `_blank`, `_parent`,
-or `_top`, default: `false`).
+or `_top`, default: `undefined`).
 Can also be a function called with the current element to get `target`
 dynamically.
-Pass `false` to not set `target`s on links.
+The default (nothing) is to not set `target`s on links.
 
-> 👉 **Note**: [you should likely pass `false`][css-tricks].
+> 👉 **Note**: [you should likely not configure this][css-tricks].
 
 ###### `options.rel`
 
@@ -176,7 +176,7 @@ Taking the above `example.js` and applying the following diff:
  const file = await unified()
    .use(remarkParse)
    .use(remarkRehype)
--  .use(rehypeExternalLinks, {target: false, rel: ['nofollow']})
+-  .use(rehypeExternalLinks, {rel: ['nofollow']})
 +  .use(rehypeExternalLinks, {
 +    target(element) {
 +      return element.properties && element.properties.id === '5'
@@ -189,7 +189,7 @@ Taking the above `example.js` and applying the following diff:
    .process('[rehype](https://github.com/rehypejs/rehype)')
 ```
 
-Changes to only apply `target="_blank"` on the element with an `id="5"`.
+Changes to apply `target="_blank"` on the element with an `id="5"`.
 
 ## Types
 

test.js

@@ -84,11 +84,11 @@ test('rehypeExternalLinks', async (t) => {
     String(
       await rehype()
         .use({settings: {fragment: true}})
-        .use(rehypeExternalLinks, {target: false})
+        .use(rehypeExternalLinks)
         .process('<a href="http://example.com">http</a>')
     ),
     '<a href="http://example.com" rel="nofollow">http</a>',
-    'should not add a `[target]` w/ `target: false`'
+    'should not add a `[target]` by default'
   )
 
   t.equal(
@@ -110,29 +110,29 @@ test('rehypeExternalLinks', async (t) => {
         .process('<a href="http://example.com">http</a>')
     ),
     '<a href="http://example.com" target="_parent">http</a>',
-    'should not add a `[target]` w/ `target` set to a known target'
+    'should add a `[target]` w/ `target` set to a known target'
   )
 
   t.equal(
     String(
       await rehype()
         .use({settings: {fragment: true}})
-        .use(rehypeExternalLinks, {target: false, rel: 'nofollow'})
+        .use(rehypeExternalLinks, {rel: 'nofollow'})
         .process('<a href="http://example.com">http</a>')
     ),
     '<a href="http://example.com" rel="nofollow">http</a>',
-    'should not add a `[rel]` w/ `rel` set to a string'
+    'should add a `[rel]` w/ `rel` set to a string'
   )
 
   t.equal(
     String(
       await rehype()
         .use({settings: {fragment: true}})
-        .use(rehypeExternalLinks, {target: false, rel: ['nofollow']})
+        .use(rehypeExternalLinks, {rel: ['nofollow']})
         .process('<a href="http://example.com">http</a>')
     ),
     '<a href="http://example.com" rel="nofollow">http</a>',
-    'should not add a `[rel]` w/ `rel` set to an array'
+    'should add a `[rel]` w/ `rel` set to an array'
   )
 
   t.equal(
@@ -256,7 +256,7 @@ test('rehypeExternalLinks', async (t) => {
               return true
             })
 
-            return noImage ? '_blank' : false
+            return noImage ? '_blank' : undefined
           },
           rel(node) {
             // True, If node doesn't contains an image