Add flycheck eslint adapter.

This code is merely an adaptation for flycheck
eslint to use `source' instead of `source-original'
as the argument for commandline.

For more details, ref:
flycheck/flycheck#2011

bvr-flycheck-eslint.el

@@ -0,0 +1,83 @@
+;;; bvr-flycheck-eslint --- Flycheck eslint adaptor
+;;; ---------------------------------------------------
+
+;;; Usage:
+;;; ---------------------------------------------------
+;;; Include this in your load-path, and either, with
+;;; use-package :
+;;;
+;;; (use-package bvr-flycheck-eslint)
+;;;
+;;; or otherwise simply
+;;;
+;;; (require 'bvr-flycheck-eslint)
+
+;;; Commentary:
+;;; ---------------------------------------------------
+;;; This code is merely an adaptation for flycheck
+;;; eslint to use `source' instead of `source-original'
+;;; as the argument for commandline.
+;;;
+;;; For more details, ref:
+;;; https://github.com/flycheck/flycheck/issues/2011
+
+;;; Code:
+;;; ---------------------------------------------------
+(defun bvr-flycheck-eslint--find-working-directory (_checker)
+ "Look for a working directory to run ESLint CHECKER in.
+
+This will be the directory that contains the `node_modules'
+directory. If no such directory is found in the directory
+hierarchy, it looks first for `.eslintignore' and then for
+`.eslintrc' files to detect the project root."
+ (let* ((file (or (buffer-file-name) default-directory)))
+ (when file
+ (or (locate-dominating-file file "node_modules")
+ (locate-dominating-file file ".eslintignore")
+ (locate-dominating-file file ".eslintrc")
+ (locate-dominating-file file ".eslintrc.js")
+ (locate-dominating-file file ".eslintrc.json")
+ (locate-dominating-file file ".eslintrc.yaml")
+ (locate-dominating-file file ".eslintrc.yml")))))
+
+
+
+(flycheck-define-checker bvr-javascript-eslint
+ "A Javascript syntax and style checker using eslint.
+
+See URL `https://eslint.org/'."
+ :command ("eslint" "--format=json"
+ (option-list "--rulesdir" flycheck-eslint-rules-directories)
+ (eval flycheck-eslint-args)
+ "--stdin" "--stdin-filename" source)
+ :standard-input t
+ :error-parser flycheck-parse-eslint
+ :enabled (lambda () (flycheck-eslint-config-exists-p))
+ :modes (js-mode js-jsx-mode js2-mode js2-jsx-mode js3-mode rjsx-mode
+ typescript-mode js-ts-mode typescript-ts-mode tsx-ts-mode)
+ :working-directory bvr-flycheck-eslint--find-working-directory
+ :verify
+ (lambda (_)
+ (let* ((default-directory
+ (flycheck-compute-working-directory 'bvr-javascript-eslint))
+ (have-config (flycheck-eslint-config-exists-p)))
+ (list
+ (flycheck-verification-result-new
+ :label "config file"
+ :message (if have-config "found" "missing or incorrect")
+ :face (if have-config 'success '(bold error))))))
+ :error-explainer
+ (lambda (err)
+ (let ((error-code (flycheck-error-id err))
+ (url "https://eslint.org/docs/rules/%s"))
+ (and error-code
+ ;; skip non-builtin rules
+ (not ;; `seq-contains-p' is only in seq >= 2.21
+ (with-no-warnings (seq-contains error-code ?/)))
+ `(url . ,(format url error-code))))))
+
+
+(add-to-list 'flycheck-checkers 'bvr-javascript-eslint)
+
+(provide 'bvr-flycheck-eslint)
+;;; bvr-flycheck-eslint.el ends here