Optimized pre-commit-hook action. (#574)

* Optimized pre-commit-hook action.
 - Added template inorder  to run grunt lint only if there are staged changes.
 - Added grunt lint-nofix task to run linter in no-fix mode.
 - Fixed some linting changes too.

* changed var to let and const keywords

* updated inline comment in grunt githooks configuration

Gruntfile.js

@@ -28,6 +28,13 @@ module.exports = function(grunt) {
           fix: true
         },
         src: ['src/**/*.js', 'test/tests/**/*.js']
+      },
+      sourceNofix: {
+        options: {
+          configFile: './.eslintrc',
+          fix: false
+        },
+        src: ['src/**/*.js', 'test/tests/**/*.js']
       }
     },
     webpack: {
@@ -59,7 +66,10 @@ module.exports = function(grunt) {
     },
     githooks: {
       all: {
-      'pre-commit':'lint' //runs linting test  before every git commit 
+        options:{
+          template:"templates/pre-commit-hook.js"
+        },
+      'pre-commit':'lint-nofix' //runs elint in -nofix mode  before every git commit 
       }
       }
   });
@@ -73,6 +83,7 @@ module.exports = function(grunt) {
   grunt.loadNpmTasks('grunt-githooks');
 
   grunt.registerTask('lint', ['eslint:source']);
+  grunt.registerTask('lint-nofix', ['eslint:sourceNofix']);
   grunt.registerTask('default', ['webpack:prod', 'decomment']);
   grunt.registerTask('dev', ['eslint','connect','webpack:dev', 'decomment']);
   grunt.registerTask('serve', 'connect:server:keepalive');

templates/pre-commit-hook.js

@@ -0,0 +1,32 @@
+ // hooks/pre-commit.js
+
+ const exec = require('child_process').exec;
+ // Executes shell commands synchronously
+ const sh = require('child_process').execSync;
+
+ exec('git diff --cached --quiet', function (err, stdout, stderr) {
+
+  // only run if there are staged changes
+  // i.e. what you would be committing if you ran "git commit" without "-a" option.
+  if (err) {
+
+  // stash unstaged changes - only test what's being committed
+  sh('git stash --keep-index --quiet');
+
+  exec('grunt {{task}}', function (err, stdout, stderr) {
+
+  console.log(stdout);
+
+  // restore stashed changes
+  sh('git stash pop --quiet');
+
+  let exitCode = 0;
+  if (err) {
+  console.log(stderr);
+  exitCode = -1;
+  }
+  process.exit(exitCode);
+  });
+  }
+
+ });