// Input
<img src="/img/tmp/catalogImage.jpg">
// Output
<picture>
<source srcset="/img/tmp/catalogImage.webp" type="image/webp">
<img src="/img/tmp/catalogImage.jpg">
</picture>
npm i --save-dev gulp-webp-html
var webpHTML = require('gulp-webp-html');
gulp.task('html',function(){
gulp.src('./assets/**/*.html')
.pipe(webpHTML())
.pipe(gulp.dest('./public/'))
});