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Source map specification


To improve and evolve the existing informal source map specification into an Ecma standard. This specification defines a JSON-based format describing a mapping of compiled/optimized code (including CSS and ECMAScript® code) into its original source, including metadata such as the mapping of certain names. The goal is to improve the development/debugging experience of source map usage, including for ECMAScript®.

Programme of work:

  1. To complete and correct the existing source map specification, including:
    • To define the source map specification strongly enough that it can be determined whether both producers and consumers are “conformant”, leading to well-defined fixes.
    • To produce a conformance test suite against this stronger definition.
    • To evolve the existing source map specification rather than creating a new system (e.g., based on DWARF).
  2. On that basis, to improve source map expressiveness in various ways, including:
    • To create additional source map capabilities for improving the mapping of names, including function, variable, and property mappings.
    • To improve the association of a source map to the code it refers to, with various possible mechanisms.


Convenor group:
Daniel Ehrenberg (Bloomberg)
Jonathan Kuperman (Bloomberg)

Secretaries: Samina Husain (Ecma International), Istvan Sebestyen (Ecma International)