##### js2json(jsfile, jsonfile, [options, ]callback)
options - replacer: the second parameter of function JSON.stringify - space : the number of spaces, default 2
example
` var js2json= require('js-2-json-file');
js2json.js2json('./package1.js', './package1.json', function () {
console.log('finished');
});
`
##### json2js(jsonfile, jsfile, [options, ]callback)
options - prefix : the chars added to the head of file, default use strict - replacer: the second parameter of function JSON.stringify - space : the number of spaces, default 2
example
` var js2json= require('js-2-json-file');
js2json.json2js('./package1.json', './package1.js', function () {
console.log('finished');
});
`