Source Map is a collection of mappings from a generated (often minified) file to the original source code (across multiple files if needed).

Create an empty source map.

SourceMap.empty
    |> SourceMap.encode


{-->


{
  "version": 3,
  "sources": [],
  "names": [],
  "mappings": ""
}


-}

Add an output filename to a source map.

SourceMap.empty
    |> SourceMap.withFile "hello.js"
    |> SourceMap.encode


{-->


{
  "version": 3,
  "sources": [],
  "names": [],
  "mappings": "",
  "file": "hello.js"
}


-}

Add a source root to a source map. This will be an automatic prefix to all the source paths mentioned in the mappings, and you can use paths relative to the root in all the added mappings.

SourceMap.empty
    |> SourceMap.withSourceRoot "https://example.com/public/js/"
    |> SourceMap.encode


{-->


{
  "version": 3,
  "sources": [],
  "names": [],
  "mappings": "",
  "sourceRoot": "https://example.com/public/js/"
}


-}

Mapping points from the generated file to some original source code.

The source field should, when prefixed with the SourceMap's sourceRoot, give a resolvable URL: the browser will try to reach it. (The spec also allows for embedding the source code in the source map, but support for that is currently TODO here.)

The optional name field specifies what was the original name of the variable (it could be mangled or removed during compilation/minification).

Add a mapping to the source map.

SourceMap.empty
    |> SourceMap.addMapping (Mapping 10 35 "foo.js" 33 2 (Just "christopher"))

Add multiple mappings to the source map at once.

SourceMap.empty
    |> SourceMap.addMappings
        [ Mapping 1 1 "a.js" 2 2 (Just "foo")
        , Mapping 3 3 "b.js" 4 4 (Just "bar")
        ]

Compile the source map into a JSON value.

SourceMap.empty
    |> SourceMap.withFile "source-mapped.js"
    |> SourceMap.addMapping (Mapping 10 35 "foo.js" 33 2 (Just "christopher"))
    |> SourceMap.encode


{-->


{
  "version": 3,
  "sources": [
    "foo.js"
  ],
  "names": [
    "christopher"
  ],
  "mappings": ";;;;;;;;;mCAgCEA",
  "file": "source-mapped.js"
}


-}