concat files in order
# NPM
npm i -s serial-concat-files
# YARN
yarn add serial-concat-files
var concat = require('serial-concat-files')()
concat(['./test/a', './test/b', './test/b'], './test/files/allc')
// OR
var concat = require('serial-concat-files')({
post: '<POST>', //
last:'<LAST>',
first:'<FIRST>',
pre:'<PRE>'
})
concat(['./test/a', './test/b', './test/b'], './test/files/allc', function (error) {
// <FIRST>this is a<POST><PRE>this is b<POST><PRE>this is b<LAST>
})