Asynchronous concat with source maps

NPM module for concatenating files and generating source maps.

Advantage over concat-with-sourcemaps

The original concat-with-sourcemaps module uses system memory (RAM) to store the concatencated files. While it makes concatenation fast, this can be a problem for machines with less RAM. This module addresses this problem by (optionally) storing the concatenated contents into a temporary file while allowing the Node.js's garbage collector to free some memory used in storing the file contents.

Installation

npm i async-concat-with-sourcemaps

Usage example

async function usingAsyncConcat() {
  // store concatenated file in /tmp directory
  var concat = new Concat(true, 'all.js', '\n', '/tmp');
  await concat.add(null, "// (c) John Doe");
  await concat.add('file1.js', file1Content);
  await concat.add('file2.js', file2Content, file2SourceMap);

  var concatenatedContent = await concat.content();
  var sourceMapForContent = await concat.sourceMap();
}

API

new Concat(generateSourceMap, outFileName, separator)

Initialize a new concat object.

Parameters:

• generateSourceMap: whether or not to generate a source map (default: false)
• outFileName: the file name/path of the output file (for the source map)
• separator: the string that should separate files (default: no separator)
• tmpDir: (optional) directory used to store concatencated files. Passing undefined will use system memory.

concat.add(fileName, content, sourceMap)

Add a file to the output file. Returns a Promise<void>.

Parameters:

• fileName: file name of the input file (can be null for content without a file reference, e.g. a license comment)
• content: content (Buffer or string) of the input file
• sourceMap: optional source map of the input file (string). Will be merged into the output source map.

concat.content()

The resulting concatenated file content (Buffer). Returns a Promise<Buffer>.

concat.sourceMap()

The resulting source map of the concatenated files (string). Returns a Promise<string | undefined>.

concat.tmpFile

Path to the temporary file.