vant-weapp/build/compiler.js

const gulp = require('gulp');
const path = require('path');
const less = require('gulp-less');
const ts = require('gulp-typescript');
const insert = require('gulp-insert');
const rename = require('gulp-rename');
const cssmin = require('gulp-clean-css');
const postcss = require('gulp-postcss');

const tsProject = ts.createProject(path.resolve(__dirname, '../tsconfig.json'));
const isProduction = process.env.NODE_ENV === 'production';
const src = path.join(__dirname, '../packages');
const dist = path.join(__dirname, isProduction ? '../dist' : '../example/dist');
const ext = ['ts', 'less', 'json', 'wxml', 'wxs'];

function copy(ext) {
  return gulp.src([src + '/**/*.' + ext]).pipe(gulp.dest(dist));
}

gulp.task('compile-less', () => {
  return gulp
    .src([src + '/**/*.less'])
    .pipe(less())
    .pipe(postcss())
    .pipe(cssmin())
    .pipe(
      insert.transform((contents, file) => {
        if (!file.path.includes('packages' + path.sep + 'common')) {
          contents = `@import '../common/index.wxss';` + contents;
        }
        return contents;
      })
    )
    .pipe(
      rename(path => {
        path.extname = '.wxss';
      })
    )
    .pipe(gulp.dest(dist));
});

gulp.task('compile-ts', () =>
  tsProject
    .src()
    .pipe(tsProject())
    .on('error', () => {})
    .pipe(gulp.dest(dist))
);
gulp.task('compile-wxs', () => copy('wxs'));
gulp.task('compile-json', () => copy('json'));
gulp.task('compile-wxml', () => copy('wxml'));
gulp.task('build', ext.map(ext => 'compile-' + ext));
gulp.start('build');

if (!isProduction) {
  ext.forEach(ext => {
    gulp.watch(src + '/**/*.' + ext, ['compile-' + ext]);
  });
}