compress.js
2.54 KB
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var zlib = require('zlib');
var Readable = require('stream').Readable;
var toArray = require('stream-to-array');
function convertContentsToBuffer(contents, callback) {
if (contents instanceof Buffer) {
callback(null, contents);
} else {
toArray(contents, function (err, chunks) {
if (err) {
callback(err, null);
return;
}
callback(null, Buffer.concat(chunks));
});
}
}
function convertContentsToStream(contents, callback) {
if (contents instanceof Readable) {
callback(null, contents);
} else {
var rs = new Readable({ objectMode: true });
rs._read = function() {
rs.push(contents);
rs.push(null);
};
callback(null, rs);
}
}
module.exports = function(originalContents, options, callback) {
convertContentsToBuffer(originalContents, function(err, contentsAsBuffer) {
if (err) {
callback(err, null, false);
return;
}
var originalContentLength = contentsAsBuffer.length;
// Check if the threshold option is set
// If true, check if the buffer length is greater than the threshold
if (options.threshold && originalContentLength < options.threshold) {
// File size is smaller than the threshold
// Pass it along to the next plugin without compressing
if (originalContents instanceof Buffer) {
callback(null, contentsAsBuffer, false);
} else {
convertContentsToStream(contentsAsBuffer, function(err, contentsAsStream) {
callback(null, contentsAsStream, false);
});
}
return;
}
convertContentsToStream(contentsAsBuffer, function(err, contentsAsStream) {
if (err) {
callback(err, null, false);
return;
}
// Compress the contents
var gzipStream = zlib.createGzip(options.gzipOptions);
contentsAsStream.pipe(gzipStream);
convertContentsToBuffer(gzipStream, function(err, compressedContentsAsBuffer) {
if (err) {
callback(err, null, false);
return;
}
if (options.skipGrowingFiles && compressedContentsAsBuffer.length >= originalContentLength) {
callback(null, originalContents, false);
} else {
if (originalContents instanceof Buffer) {
callback(null, compressedContentsAsBuffer, true);
} else {
convertContentsToStream(compressedContentsAsBuffer, function(err, compressedContentsStream) {
callback(null, compressedContentsStream, true);
});
}
}
});
});
});
};