gulp-minifying-task.js

const htmlmin = require("gulp-htmlmin");
//...
gulp.task("minify-html", function(done) {
  let publicFolder = "./public";
  let html = publicFolder + "/**/*.html";
  let css = publicFolder + "/**/*.css";
  let js = publicFolder + "/**/*.js";
  let dest = "./dist";
  log("Minifying HTML/CSS/JS in '" + publicFolder + "' to '" + dest + "'");
  gulp.src(publicFolder + "/**")
    .pipe(gulp.dest(dest));
  gulp.src([html, css, js])
    .pipe(htmlmin({ collapseWhitespace: true }))
    .pipe(gulp.dest(dest))
    .on("end", done);
});