istanbul-lib-source-maps

What is istanbul-lib-source-maps?

The istanbul-lib-source-maps package is used for handling source maps in the context of the Istanbul code coverage tool. It allows for the generation, manipulation, and consumption of source maps, which are files that map from the transformed source to the original source, enabling the accurate reporting of code coverage for projects that use transpilers or minifiers.

What are istanbul-lib-source-maps's main functionalities?

Source Map Consumption

This feature allows for the consumption of source maps by registering them with a source map store. This is useful for tools that need to map coverage information back to the original source files.

const sourceMaps = require('istanbul-lib-source-maps');
const mapStore = sourceMaps.createSourceMapStore();
mapStore.registerURL('compiled.js', 'compiled.js.map');

Source Map Generation

This feature enables the generation of source maps. It's particularly useful for developers who are compiling or transforming their code and need to produce source maps for accurate code coverage reporting.

const {SourceMapGenerator} = require('istanbul-lib-source-maps');
let generator = new SourceMapGenerator({file: 'output.js'});
generator.addMapping({
  generated: {line: 1, column: 0},
  source: 'input.js',
  original: {line: 1, column: 0}
});
let map = generator.toString();

Applying Source Maps to Coverage Data

This feature involves applying source maps to coverage data to remap coverage reports back to the original source code. This is crucial for accurate coverage reporting in projects that use transpilation or other code transformations.

const sourceMaps = require('istanbul-lib-source-maps');
const mapStore = sourceMaps.createSourceMapStore();
mapStore.registerURL('compiled.js', 'compiled.js.map');
const transformedCoverage = mapStore.transformCoverage(mapStore.loadCoverage(coverageObject));

Other packages similar to istanbul-lib-source-maps

source-map

The source-map package provides functionalities for generating and consuming source maps. It is a lower-level library compared to istanbul-lib-source-maps, which is specifically tailored for use with Istanbul's code coverage tools. source-map is more general-purpose and can be used in a wider range of applications.

remap-istanbul

remap-istanbul is a tool for remapping code coverage information using source maps. It serves a similar purpose to istanbul-lib-source-maps but operates as a standalone tool rather than a library. It can be used to generate remapped coverage reports in various formats.

README

istanbul-lib-source-maps

Source map support for istanbuljs.

Debugging

istanbul-lib-source-maps uses the debug module. Run your application with the environment variable DEBUG=istanbuljs, to receive debug output.