@jridgewell/gen-mapping
Advanced tools
Package description
The @jridgewell/gen-mapping package is a library for generating source maps, which are used to map the transformed source to the original source, enabling developers to debug their code more easily after it has been compiled or minified. It provides a simple API for adding mappings and generating the source map.
Creating a new source map generator
This feature allows you to create a new source map generator instance, specifying the output file name for the source map.
{"const { GenMapping } = require('@jridgewell/gen-mapping');
const map = new GenMapping({
file: 'minified.js'
});
}Adding mappings to the source map
This feature allows you to add individual mappings to the source map, linking a location in the generated file to a location in the original source file.
{"const { addMapping } = require('@jridgewell/gen-mapping');
addMapping(map, {
generated: { line: 1, column: 5 },
source: 'original.js',
original: { line: 1, column: 30 }
});
}Generating the source map
This feature generates the final source map from the added mappings, which can then be used by browsers or other tools to map the transformed source back to the original source.
{"const { toMapping } = require('@jridgewell/gen-mapping');
const sourceMap = toMapping(map);
}The 'source-map' package provides similar functionality for generating source maps. It offers a more comprehensive API for manipulating source maps, including parsing and merging existing source maps, which @jridgewell/gen-mapping does not provide.
The 'source-map-js' package is a fork of the 'source-map' library that focuses on performance improvements and bug fixes. It is similar to @jridgewell/gen-mapping in that it generates source maps, but it also includes features for parsing and manipulating source maps.
The 'magic-string' package is designed for manipulating strings and generating source maps in the process. It is different from @jridgewell/gen-mapping in that it provides a higher-level API for string manipulation, which includes source map generation as a byproduct of those manipulations.
Readme
Generate source maps
gen-mapping allows you to generate a source map during transpilation or minification.
With a source map, you're able to trace the original location in the source file, either in Chrome's
DevTools or using a library like @jridgewell/trace-mapping.
You may already be familiar with the source-map package's SourceMapGenerator. This
provides the same addMapping and setSourceContent API.
npm install @jridgewell/gen-mapping
import { GenMapping, addMapping, setSourceContent, encodedMap } from '@jridgewell/gen-mapping';
const map = new GenMapping({
file: 'output.js',
sourceRoot: 'https://example.com/',
});
setSourceContent(map, 'input.js', `function foo() {}`);
addMapping(map, {
// Lines start at line 1, columns at column 0.
generated: { line: 1, column: 0 },
source: 'input.js',
original: { line: 1, column: 0 },
});
addMapping(map, {
generated: { line: 1, column: 9 },
source: 'input.js',
original: { line: 1, column: 9 },
name: 'foo',
});
assert.deepEqual(encodedMap(map), {
version: 3,
file: 'output.js',
names: ['foo'],
sourceRoot: 'https://example.com/',
sources: ['input.js'],
sourcesContent: ['function foo() {}'],
mappings: 'AAAA,SAASA',
});
FAQs
Generate source maps
The npm package @jridgewell/gen-mapping receives a total of 36,798,723 weekly downloads. As such, @jridgewell/gen-mapping popularity was classified as popular.
We found that @jridgewell/gen-mapping demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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