gulpファイル

// plugin
const gulp         = require('gulp');
const sass         = require('gulp-sass');
const plumber      = require('gulp-plumber');
const notify       = require('gulp-notify');
const fibers = require("fibers");
const autoprefixer = require('gulp-autoprefixer');
sass.compiler = require("sass");
const fs = require("fs");

// sass compile
gulp.task('sass',()=>{
  return gulp
    .src("./scss/*.scss")
    .pipe(
      plumber({ errorHandler: notify.onError("Error: <%= error.message %>") })
    )
    .pipe(
      sass({
        fiber: fibers,
        style: "expanded",
      })
    )
    .pipe(
      autoprefixer({
        browsers: ["last 2 versions"],
        cascade: false,
      })
    )
    .pipe(gulp.dest("./css"));
});


gulp.task('watch', ()=>{
  gulp.watch('./scss/**/*.scss', ['sass']);
});

gulp.task('default',['watch']);