ESlint linting gulpfile.js

Question

Hi i use Atom and plugin called lint-eslint for linting my javascript code and it does work fine but i have one really annoying linting error on my gulpfile.js

Here is the code that triggers linting error, i'm using airbnb .eslintrc configuration file for ESlinter.

gulp.task('lint', () => {
 return gulp.src(['**/*.js', '!node_modules/**', '!src/**'])
 .pipe(gulpif(args.verbose, gprint()))
 .pipe(eslint())
 .pipe(eslint.format())
 .pipe(eslint.failAfterError());
});

Note that i'm trying to use arrow syntax. I'm getting following error Unexpected block statement surrounding arrow body. And when i remove the return it goes away.

It has to do with the early return stream from gulp src is there some other way to return it or how do i correct the error i know i can ignore the file but i want to know if there is another way to return gulp.src()

Answer 1

Since your function simply return a value, you can omit the curly braces {} and the return statement, which makes the code lighter and easier to read.

The rule involved is arrow-body-style which "enforces the consistent use of braces in arrow functions" .

gulp.task('lint', () => 
  gulp.src(['**/*.js', '!node_modules/**', '!src/**'])
   .pipe(gulpif(args.verbose, gprint()))
   .pipe(eslint())
   .pipe(eslint.format())
   .pipe(eslint.failAfterError())
);

Answer 2

ES6 arrow function can return an object without word 'return' like this:

let func = () => ({key: 'value'});
let a = func();   // and a will be an object {key: 'value'}

This is ES6 standard.

And eslint-airbnb style guide believes that if your arrow function does nothing but return an object, the 'return' will not be necessary. So your code could go like this:

gulp.task('lint', () => (
 gulp.src(['**/*.js', '!node_modules/**', '!src/**'])
  .pipe(gulpif(args.verbose, gprint()))
  .pipe(eslint())
  .pipe(eslint.format())
  .pipe(eslint.failAfterError())
));

See more: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions about Returning object literals.