index.js
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"use strict";
var etag = require("etag");
var fresh = require("fresh");
var fs = require("fs");
var path = require("path");
var zlib = require("zlib");
var minifiedScript = path.join(__dirname, "/dist/index.min.js");
var unminifiedScript = path.join(__dirname, "/dist/index.js");
/**
* Does the current request support compressed encoding?
* @param {Object} req
* @returns {boolean}
*/
function supportsGzip (req) {
var accept = req.headers['accept-encoding'];
return accept && accept.indexOf('gzip') > -1;
}
/**
* Set headers on the response
* @param {Object} res
* @param {String} body
*/
function setHeaders(res, body) {
res.setHeader("Cache-Control", "public, max-age=0");
res.setHeader("Content-Type", "text/javascript");
res.setHeader("ETag", etag(body));
}
/**
* @param {Object} options
* @param {String} connector
* @returns {String}
*/
function getScriptBody(options, connector) {
var script = minifiedScript;
if (options && !options.minify) {
script = unminifiedScript;
}
return connector + fs.readFileSync(script);
}
/**
* @param {Object} req
* @returns {String}
*/
function isConditionalGet(req) {
return req.headers["if-none-match"] || req.headers["if-modified-since"];
}
/**
* Return a not-modified response
* @param {Object} res
*/
function notModified(res) {
res.removeHeader("Content-Type");
res.statusCode = 304;
res.end();
}
/**
* Public method for returning either a middleware fn
* or the content as a string
* @param {Object} options
* @param {String} connector - content to be prepended
* @param {String} type - either `file` or `middleware`
* @returns {*}
*/
function init(options, connector, type) {
var gzipCached;
/**
* Combine string to create the final version
* @type {String}
*/
var requestBody = getScriptBody(options, connector);
/**
* If the user asked for a file, simply return the string.
*/
if (type && type === "file") {
return requestBody;
}
/**
* Otherwise return a function to be used a middleware
*/
return function (req, res) {
/**
* default to using the uncompressed string
* @type {String}
*/
var output = requestBody;
/**
* Set the appropriate headers for caching
*/
setHeaders(res, output);
if (isConditionalGet(req) && fresh(req.headers, res._headers)) {
return notModified(res);
}
/**
* If gzip is supported, compress the string once
* and save for future requests
*/
if (supportsGzip(req)) {
res.setHeader("Content-Encoding", "gzip");
if (!gzipCached) {
var buf = new Buffer(output, "utf-8");
zlib.gzip(buf, function (_, result) {
gzipCached = result;
res.end(result);
});
} else {
res.end(gzipCached);
}
} else {
res.end(output);
}
};
}
module.exports.middleware = init;
module.exports.plugin = init;
module.exports.minified = function () {
return fs.readFileSync(minifiedScript, 'utf8');
};
module.exports.unminified = function () {
return fs.readFileSync(unminifiedScript, 'utf8');
}