Change to support code points, support astrals

Author: wooorm

lib/index.js

@@ -3,29 +3,29 @@ const contRe = /[$_\u{200C}\u{200D}\p{ID_Continue}]/u
 const re = /^[$_\p{ID_Start}][$_\u{200C}\u{200D}\p{ID_Continue}]*$/u
 
 /**
- * Checks if the given character code can start an identifier.
+ * Checks if the given code point can start an identifier.
  *
- * @param {number} code
- *   Character code to check.
+ * @param {number | undefined} code
+ *   Code point to check.
  * @returns {boolean}
  *   Whether `code` can start an identifier.
  */
-// To do: support astrals.
+// Note: `undefined` is supported so you can pass the result from `''.codePointAt`.
 export function start(code) {
-  return startRe.test(String.fromCharCode(code))
+  return code ? startRe.test(String.fromCodePoint(code)) : false
 }
 
 /**
- * Checks if the given character code can continue an identifier.
+ * Checks if the given code point can continue an identifier.
  *
- * @param {number} code
- *   Character code to check.
+ * @param {number | undefined} code
+ *   Code point to check.
  * @returns {boolean}
  *   Whether `code` can continue an identifier.
  */
-// To do: support astrals.
+// Note: `undefined` is supported so you can pass the result from `''.codePointAt`.
 export function cont(code) {
-  return contRe.test(String.fromCharCode(code))
+  return code ? contRe.test(String.fromCodePoint(code)) : false
 }
 
 /**

package.json

@@ -58,11 +58,7 @@
     "trailingComma": "none"
   },
   "xo": {
-    "prettier": true,
-    "rules": {
-      "no-misleading-character-class": "off",
-      "unicorn/prefer-code-point": "off"
-    }
+    "prettier": true
   },
   "remarkConfig": {
     "plugins": [

readme.md

@@ -68,8 +68,8 @@ name('$something69') // => true
 name('69') // => false
 name('var') // => true (this does not handle keywords)
 
-start(48) // => false (character code for `0`)
-cont(48) // => true (character code for `0`)
+start(48) // => false (code point for `'0'`)
+cont(48) // => true (code point for `'0'`)
 ```
 
 ## API
@@ -80,12 +80,12 @@ There is no default export.
 
 ### `cont(code)`
 
-Checks if the given character code can continue an identifier.
+Checks if the given code point can continue an identifier.
 
 ###### Parameters
 
 *   `code` (`number`)
-    — character code to check
+    — code point to check
 
 ###### Returns
 
@@ -106,12 +106,12 @@ Whether `name` can be an identifier (`boolean`).
 
 ### `start(code)`
 
-Checks if the given character code can start an identifier.
+Checks if the given code point can start an identifier.
 
 ###### Parameters
 
 *   `code` (`number`)
-    — character code to check
+    — code point to check
 
 ###### Returns
 

test.js

@@ -10,15 +10,35 @@ test('isIdentifierName', () => {
     'should expose the public api'
   )
 
-  assert.ok(start('a'.charCodeAt(0)), 'should say `a` is a start code')
-  assert.ok(start('_'.charCodeAt(0)), 'should say `_` is a start code')
-  assert.ok(!start('1'.charCodeAt(0)), 'should not say `1` is a start code')
-  assert.ok(!start('-'.charCodeAt(0)), 'should not say `-` is a start code')
+  assert.ok(
+    !start(''.codePointAt(0)),
+    'should not say `undefined` is a start code'
+  )
+  assert.ok(start('a'.codePointAt(0)), 'should say `a` is a start code')
+  assert.ok(start('_'.codePointAt(0)), 'should say `_` is a start code')
+  assert.ok(!start('1'.codePointAt(0)), 'should not say `1` is a start code')
+  assert.ok(!start('-'.codePointAt(0)), 'should not say `-` is a start code')
+  assert.ok(start('ಠ'.codePointAt(0)), 'should say `ಠ` is a start code')
+  assert.ok(
+    start(0x1_02_a7),
+    'should say `0xd8_00 0xde_a7` (together 0x1_02_a7) is a start code'
+  )
+  assert.ok(!start(0xd8_00), 'should not say `0xd8_00` is a start code')
 
-  assert.ok(cont('a'.charCodeAt(0)), 'should say `a` is a cont code')
-  assert.ok(cont('_'.charCodeAt(0)), 'should say `_` is a cont code')
-  assert.ok(cont('1'.charCodeAt(0)), 'should say `1` is a cont code')
-  assert.ok(!cont('-'.charCodeAt(0)), 'should not say `-` is a cont code')
+  assert.ok(
+    !cont(''.codePointAt(0)),
+    'should not say `undefined` is a cont code'
+  )
+  assert.ok(cont('a'.codePointAt(0)), 'should say `a` is a cont code')
+  assert.ok(cont('_'.codePointAt(0)), 'should say `_` is a cont code')
+  assert.ok(cont('1'.codePointAt(0)), 'should say `1` is a cont code')
+  assert.ok(!cont('-'.codePointAt(0)), 'should not say `-` is a cont code')
+  assert.ok(cont('ಠ'.codePointAt(0)), 'should say `ಠ` is a cont code')
+  assert.ok(
+    cont(0x1_02_a7),
+    'should say `0xd8_00 0xde_a7` (together 0x1_02_a7) is a cont code'
+  )
+  assert.ok(!cont(0xd8_00), 'should not say `0xd8_00` is a cont code')
 
   assert.ok(!name(''), 'should not say `` (empty string) is a name')
   assert.ok(name('a'), 'should say `a` is a name')
@@ -30,4 +50,6 @@ test('isIdentifierName', () => {
   assert.ok(name('_a$b9'), 'should say `_a$b9` is a name')
   assert.ok(!name('aaa-'), 'should not say `aaa-` is a name')
   assert.ok(!name('-aaa'), 'should not say `-aaa` is a name')
+  assert.ok(name('ಠ_ಠ'), 'should say `ಠ_ಠ` is a name')
+  assert.ok(name('𐊧'), 'should say `𐊧` (0x1_02_a7) is a name')
 })