gulp-yhtml

var gulp = require('gulp');
var contentInclude = require('gulp-content-includer');
 
gulp.task('concat',function() {
    gulp.src("./content.html")
        .pipe(contentInclude({
            includerReg:/<!\-\-include\s+"([^"]+)"\-\->/g
        }))
        .pipe(gulp.dest('./'));
});