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@jridgewell/gen-mapping

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@jridgewell/gen-mapping

Generate source maps

    0.3.2latest

Version published
Maintainers
1
Weekly downloads
36,294,370
decreased by-10.72%

Weekly downloads

Changelog

Source

v0.3.2

Internal

  • [meta] fix "exports" for node 13.0-13.6 by @ljharb in https://github.com/jridgewell/gen-mapping/pull/4
  • Fix built sources paths

New Contributors

  • @ljharb made their first contribution in https://github.com/jridgewell/gen-mapping/pull/4

Full Changelog: https://github.com/jridgewell/gen-mapping/compare/v0.3.1...v0.3.2

Readme

Source

@jridgewell/gen-mapping

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.

Installation

npm install @jridgewell/gen-mapping

Usage

import { GenMapping, addMapping, setSourceContent, toEncodedMap, toDecodedMap } 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(toDecodedMap(map), { version: 3, file: 'output.js', names: ['foo'], sourceRoot: 'https://example.com/', sources: ['input.js'], sourcesContent: ['function foo() {}'], mappings: [ [ [0, 0, 0, 0], [9, 0, 0, 9, 0] ] ], }); assert.deepEqual(toEncodedMap(map), { version: 3, file: 'output.js', names: ['foo'], sourceRoot: 'https://example.com/', sources: ['input.js'], sourcesContent: ['function foo() {}'], mappings: 'AAAA,SAASA', });

Smaller Sourcemaps

Not everything needs to be added to a sourcemap, and needless markings can cause signficantly larger file sizes. gen-mapping exposes maybeAddSegment/maybeAddMapping APIs that will intelligently determine if this marking adds useful information. If not, the marking will be skipped.

import { maybeAddMapping } from '@jridgewell/gen-mapping'; const map = new GenMapping(); // Adding a sourceless marking at the beginning of a line isn't useful. maybeAddMapping(map, { generated: { line: 1, column: 0 }, }); // Adding a new source marking is useful. maybeAddMapping(map, { generated: { line: 1, column: 0 }, source: 'input.js', original: { line: 1, column: 0 }, }); // But adding another marking pointing to the exact same original location isn't, even if the // generated column changed. maybeAddMapping(map, { generated: { line: 1, column: 9 }, source: 'input.js', original: { line: 1, column: 0 }, }); assert.deepEqual(toEncodedMap(map), { version: 3, names: [], sources: ['input.js'], sourcesContent: [null], mappings: 'AAAA', });

Benchmarks

node v18.0.0 amp.js.map Memory Usage: gen-mapping: addSegment 5852872 bytes gen-mapping: addMapping 7716042 bytes source-map-js 6143250 bytes source-map-0.6.1 6124102 bytes source-map-0.8.0 6121173 bytes Smallest memory usage is gen-mapping: addSegment Adding speed: gen-mapping: addSegment x 441 ops/sec ±2.07% (90 runs sampled) gen-mapping: addMapping x 350 ops/sec ±2.40% (86 runs sampled) source-map-js: addMapping x 169 ops/sec ±2.42% (80 runs sampled) source-map-0.6.1: addMapping x 167 ops/sec ±2.56% (80 runs sampled) source-map-0.8.0: addMapping x 168 ops/sec ±2.52% (80 runs sampled) Fastest is gen-mapping: addSegment Generate speed: gen-mapping: decoded output x 150,824,370 ops/sec ±0.07% (102 runs sampled) gen-mapping: encoded output x 663 ops/sec ±0.22% (98 runs sampled) source-map-js: encoded output x 197 ops/sec ±0.45% (84 runs sampled) source-map-0.6.1: encoded output x 198 ops/sec ±0.33% (85 runs sampled) source-map-0.8.0: encoded output x 197 ops/sec ±0.06% (93 runs sampled) Fastest is gen-mapping: decoded output *** babel.min.js.map Memory Usage: gen-mapping: addSegment 37578063 bytes gen-mapping: addMapping 37212897 bytes source-map-js 47638527 bytes source-map-0.6.1 47690503 bytes source-map-0.8.0 47470188 bytes Smallest memory usage is gen-mapping: addMapping Adding speed: gen-mapping: addSegment x 31.05 ops/sec ±8.31% (43 runs sampled) gen-mapping: addMapping x 29.83 ops/sec ±7.36% (51 runs sampled) source-map-js: addMapping x 20.73 ops/sec ±6.22% (38 runs sampled) source-map-0.6.1: addMapping x 20.03 ops/sec ±10.51% (38 runs sampled) source-map-0.8.0: addMapping x 19.30 ops/sec ±8.27% (37 runs sampled) Fastest is gen-mapping: addSegment Generate speed: gen-mapping: decoded output x 381,379,234 ops/sec ±0.29% (96 runs sampled) gen-mapping: encoded output x 95.15 ops/sec ±2.98% (72 runs sampled) source-map-js: encoded output x 15.20 ops/sec ±7.41% (33 runs sampled) source-map-0.6.1: encoded output x 16.36 ops/sec ±10.46% (31 runs sampled) source-map-0.8.0: encoded output x 16.06 ops/sec ±6.45% (31 runs sampled) Fastest is gen-mapping: decoded output *** preact.js.map Memory Usage: gen-mapping: addSegment 416247 bytes gen-mapping: addMapping 419824 bytes source-map-js 1024619 bytes source-map-0.6.1 1146004 bytes source-map-0.8.0 1113250 bytes Smallest memory usage is gen-mapping: addSegment Adding speed: gen-mapping: addSegment x 13,755 ops/sec ±0.15% (98 runs sampled) gen-mapping: addMapping x 13,013 ops/sec ±0.11% (101 runs sampled) source-map-js: addMapping x 4,564 ops/sec ±0.21% (98 runs sampled) source-map-0.6.1: addMapping x 4,562 ops/sec ±0.11% (99 runs sampled) source-map-0.8.0: addMapping x 4,593 ops/sec ±0.11% (100 runs sampled) Fastest is gen-mapping: addSegment Generate speed: gen-mapping: decoded output x 379,864,020 ops/sec ±0.23% (93 runs sampled) gen-mapping: encoded output x 14,368 ops/sec ±4.07% (82 runs sampled) source-map-js: encoded output x 5,261 ops/sec ±0.21% (99 runs sampled) source-map-0.6.1: encoded output x 5,124 ops/sec ±0.58% (99 runs sampled) source-map-0.8.0: encoded output x 5,434 ops/sec ±0.33% (96 runs sampled) Fastest is gen-mapping: decoded output *** react.js.map Memory Usage: gen-mapping: addSegment 975096 bytes gen-mapping: addMapping 1102981 bytes source-map-js 2918836 bytes source-map-0.6.1 2885435 bytes source-map-0.8.0 2874336 bytes Smallest memory usage is gen-mapping: addSegment Adding speed: gen-mapping: addSegment x 4,772 ops/sec ±0.15% (100 runs sampled) gen-mapping: addMapping x 4,456 ops/sec ±0.13% (97 runs sampled) source-map-js: addMapping x 1,618 ops/sec ±0.24% (97 runs sampled) source-map-0.6.1: addMapping x 1,622 ops/sec ±0.12% (99 runs sampled) source-map-0.8.0: addMapping x 1,631 ops/sec ±0.12% (100 runs sampled) Fastest is gen-mapping: addSegment Generate speed: gen-mapping: decoded output x 379,107,695 ops/sec ±0.07% (99 runs sampled) gen-mapping: encoded output x 5,421 ops/sec ±1.60% (89 runs sampled) source-map-js: encoded output x 2,113 ops/sec ±1.81% (98 runs sampled) source-map-0.6.1: encoded output x 2,126 ops/sec ±0.10% (100 runs sampled) source-map-0.8.0: encoded output x 2,176 ops/sec ±0.39% (98 runs sampled) Fastest is gen-mapping: decoded output

Keywords

FAQs

What is @jridgewell/gen-mapping?

Generate source maps

Is @jridgewell/gen-mapping popular?

The npm package @jridgewell/gen-mapping receives a total of 29,123,905 weekly downloads. As such, @jridgewell/gen-mapping popularity was classified as popular.

Is @jridgewell/gen-mapping well maintained?

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.

Last updated on 26 Jun 2022

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