Add 'module-type' option determining how README is linted

README.md

@@ -96,6 +96,7 @@ Many variables have default values and are therefore optional.
 | `opening-delimiter`           | `` ```javascript ``   | The opening delimiter of doctest blocks in the source files.                  |
 | `closing-delimiter`           | `` ``` ``             | The closing delimiter of doctest blocks in the source files.                  |
 | `version-tag-prefix`          | `v`                   | The prefix of annotated version tags (`version-tag-prefix =` for no prefix).  |
+| `module-type`                 | `commonjs`            | The type of module doctest should use. One of `commonjs`, `amd`, or `esm`.    |
 
 ### Custom scripts
 
@@ -122,7 +123,7 @@ Runs [`doctest`↗︎][] with suitable `--module`, `--prefix`,
 `--opening-delimiter`, and `--closing-delimiter` values.
 
 Configurable via [variables][] (`source-files`, `comment-prefix`,
-`opening-delimiter`, `closing-delimiter`).
+`opening-delimiter`, `closing-delimiter`, `module-type`).
 
 ### `generate-readme`
 
@@ -190,7 +191,8 @@ undefined link references or unused link definitions.
 Uses [`eslint`↗︎][] and [`eslint-plugin-markdown`↗︎][] to assert that the readme,
 when built, will not contain examples which violate the project's style guide.
 
-Configurable via [variables][] (`opening-delimiter`, `closing-delimiter`).
+Configurable via [variables][] (`opening-delimiter`, `closing-delimiter`
+`module-type`).
 
 ### `prepublish`
 

bin/doctest

@@ -11,12 +11,13 @@ set +f ; shopt -s nullglob
 files=($(get source-files))
 set -f ; shopt -u nullglob
 
+module="$(get module-type)"
 prefix="$(get comment-prefix)"
 opening="$(get opening-delimiter)"
 closing="$(get closing-delimiter)"
 
 node_modules/.bin/doctest \
-  --module commonjs \
+  --module "$module" \
   --prefix "$prefix" \
   --opening-delimiter "$opening" \
   --closing-delimiter "$closing" \

bin/lint-readme

@@ -68,4 +68,11 @@ node_modules/.bin/remark \
 cp README.md README.md.temp
 rewrite <README.md.temp >README.md
 
-node_modules/.bin/eslint -- README.md
+module="$(get module-type)"
+if [[ $module == 'esm' ]] ; then
+  source = 'module'
+else
+  source = 'script'
+fi
+
+node_modules/.bin/eslint --parser-options "sourceType:$source" -- README.md

functions

@@ -33,6 +33,7 @@ get() {
     closing-delimiter)      # shellcheck disable=SC2016
                             printf '```' ;;
     version-tag-prefix)     printf 'v' ;;
+    module-type)            printf 'commonjs' ;;
     *)
       echo "'$1' not defined in $config" >&2
       return 1

package.json

@@ -33,7 +33,7 @@
     "npm": ">=3.0.0"
   },
   "dependencies": {
-    "doctest": "0.16.x",
+    "doctest": "github:Avaq/doctest#avaq/esm",
     "eslint": "5.15.x",
     "eslint-plugin-markdown": "1.0.x",
     "mocha": "5.x.x",