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parttimejob/node_modules/@jridgewell/sourcemap-codec
侯晓宇 0cb2601919
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README.md

@jridgewell/sourcemap-codec

Encode/decode the mappings property of a sourcemap.

Why?

Sourcemaps are difficult to generate and manipulate, because the mappings property the part that actually links the generated code back to the original source is encoded using an obscure method called Variable-length quantity. On top of that, each segment in the mapping contains offsets rather than absolute indices, which means that you can't look at a segment in isolation you have to understand the whole sourcemap.

This package makes the process slightly easier.

Installation

npm install @jridgewell/sourcemap-codec

Usage

import { encode, decode } from '@jridgewell/sourcemap-codec';

var decoded = decode( ';EAEEA,EAAE,EAAC,CAAE;ECQY,UACC' );

assert.deepEqual( decoded, [
	// the first line (of the generated code) has no mappings,
	// as shown by the starting semi-colon (which separates lines)
	[],

	// the second line contains four (comma-separated) segments
	[
		// segments are encoded as you'd expect:
		// [ generatedCodeColumn, sourceIndex, sourceCodeLine, sourceCodeColumn, nameIndex ]

		// i.e. the first segment begins at column 2, and maps back to the second column
		// of the second line (both zero-based) of the 0th source, and uses the 0th
		// name in the `map.names` array
		[ 2, 0, 2, 2, 0 ],

		// the remaining segments are 4-length rather than 5-length,
		// because they don't map a name
		[ 4, 0, 2, 4 ],
		[ 6, 0, 2, 5 ],
		[ 7, 0, 2, 7 ]
	],

	// the final line contains two segments
	[
		[ 2, 1, 10, 19 ],
		[ 12, 1, 11, 20 ]
	]
]);

var encoded = encode( decoded );
assert.equal( encoded, ';EAEEA,EAAE,EAAC,CAAE;ECQY,UACC' );

Benchmarks

node v20.10.0

amp.js.map - 45120 segments

Decode Memory Usage:
local code                             5815135 bytes
@jridgewell/sourcemap-codec 1.4.15     5868160 bytes
sourcemap-codec                        5492584 bytes
source-map-0.6.1                      13569984 bytes
source-map-0.8.0                       6390584 bytes
chrome dev tools                       8011136 bytes
Smallest memory usage is sourcemap-codec

Decode speed:
decode: local code x 492 ops/sec ±1.22% (90 runs sampled)
decode: @jridgewell/sourcemap-codec 1.4.15 x 499 ops/sec ±1.16% (89 runs sampled)
decode: sourcemap-codec x 376 ops/sec ±1.66% (89 runs sampled)
decode: source-map-0.6.1 x 34.99 ops/sec ±0.94% (48 runs sampled)
decode: source-map-0.8.0 x 351 ops/sec ±0.07% (95 runs sampled)
chrome dev tools x 165 ops/sec ±0.91% (86 runs sampled)
Fastest is decode: @jridgewell/sourcemap-codec 1.4.15

Encode Memory Usage:
local code                              444248 bytes
@jridgewell/sourcemap-codec 1.4.15      623024 bytes
sourcemap-codec                        8696280 bytes
source-map-0.6.1                       8745176 bytes
source-map-0.8.0                       8736624 bytes
Smallest memory usage is local code

Encode speed:
encode: local code x 796 ops/sec ±0.11% (97 runs sampled)
encode: @jridgewell/sourcemap-codec 1.4.15 x 795 ops/sec ±0.25% (98 runs sampled)
encode: sourcemap-codec x 231 ops/sec ±0.83% (86 runs sampled)
encode: source-map-0.6.1 x 166 ops/sec ±0.57% (86 runs sampled)
encode: source-map-0.8.0 x 203 ops/sec ±0.45% (88 runs sampled)
Fastest is encode: local code,encode: @jridgewell/sourcemap-codec 1.4.15


***


babel.min.js.map - 347793 segments

Decode Memory Usage:
local code                            35424960 bytes
@jridgewell/sourcemap-codec 1.4.15    35424696 bytes
sourcemap-codec                       36033464 bytes
source-map-0.6.1                      62253704 bytes
source-map-0.8.0                      43843920 bytes
chrome dev tools                      45111400 bytes
Smallest memory usage is @jridgewell/sourcemap-codec 1.4.15

Decode speed:
decode: local code x 38.18 ops/sec ±5.44% (52 runs sampled)
decode: @jridgewell/sourcemap-codec 1.4.15 x 38.36 ops/sec ±5.02% (52 runs sampled)
decode: sourcemap-codec x 34.05 ops/sec ±4.45% (47 runs sampled)
decode: source-map-0.6.1 x 4.31 ops/sec ±2.76% (15 runs sampled)
decode: source-map-0.8.0 x 55.60 ops/sec ±0.13% (73 runs sampled)
chrome dev tools x 16.94 ops/sec ±3.78% (46 runs sampled)
Fastest is decode: source-map-0.8.0

Encode Memory Usage:
local code                             2606016 bytes
@jridgewell/sourcemap-codec 1.4.15     2626440 bytes
sourcemap-codec                       21152576 bytes
source-map-0.6.1                      25023928 bytes
source-map-0.8.0                      25256448 bytes
Smallest memory usage is local code

Encode speed:
encode: local code x 127 ops/sec ±0.18% (83 runs sampled)
encode: @jridgewell/sourcemap-codec 1.4.15 x 128 ops/sec ±0.26% (83 runs sampled)
encode: sourcemap-codec x 29.31 ops/sec ±2.55% (53 runs sampled)
encode: source-map-0.6.1 x 18.85 ops/sec ±3.19% (36 runs sampled)
encode: source-map-0.8.0 x 19.34 ops/sec ±1.97% (36 runs sampled)
Fastest is encode: @jridgewell/sourcemap-codec 1.4.15


***


preact.js.map - 1992 segments

Decode Memory Usage:
local code                              261696 bytes
@jridgewell/sourcemap-codec 1.4.15      244296 bytes
sourcemap-codec                         302816 bytes
source-map-0.6.1                        939176 bytes
source-map-0.8.0                           336 bytes
chrome dev tools                        587368 bytes
Smallest memory usage is source-map-0.8.0

Decode speed:
decode: local code x 17,782 ops/sec ±0.32% (97 runs sampled)
decode: @jridgewell/sourcemap-codec 1.4.15 x 17,863 ops/sec ±0.40% (100 runs sampled)
decode: sourcemap-codec x 12,453 ops/sec ±0.27% (101 runs sampled)
decode: source-map-0.6.1 x 1,288 ops/sec ±1.05% (96 runs sampled)
decode: source-map-0.8.0 x 9,289 ops/sec ±0.27% (101 runs sampled)
chrome dev tools x 4,769 ops/sec ±0.18% (100 runs sampled)
Fastest is decode: @jridgewell/sourcemap-codec 1.4.15

Encode Memory Usage:
local code                              262944 bytes
@jridgewell/sourcemap-codec 1.4.15       25544 bytes
sourcemap-codec                         323048 bytes
source-map-0.6.1                        507808 bytes
source-map-0.8.0                        507480 bytes
Smallest memory usage is @jridgewell/sourcemap-codec 1.4.15

Encode speed:
encode: local code x 24,207 ops/sec ±0.79% (95 runs sampled)
encode: @jridgewell/sourcemap-codec 1.4.15 x 24,288 ops/sec ±0.48% (96 runs sampled)
encode: sourcemap-codec x 6,761 ops/sec ±0.21% (100 runs sampled)
encode: source-map-0.6.1 x 5,374 ops/sec ±0.17% (99 runs sampled)
encode: source-map-0.8.0 x 5,633 ops/sec ±0.32% (99 runs sampled)
Fastest is encode: @jridgewell/sourcemap-codec 1.4.15,encode: local code


***


react.js.map - 5726 segments

Decode Memory Usage:
local code                              678816 bytes
@jridgewell/sourcemap-codec 1.4.15      678816 bytes
sourcemap-codec                         816400 bytes
source-map-0.6.1                       2288864 bytes
source-map-0.8.0                        721360 bytes
chrome dev tools                       1012512 bytes
Smallest memory usage is local code

Decode speed:
decode: local code x 6,178 ops/sec ±0.19% (98 runs sampled)
decode: @jridgewell/sourcemap-codec 1.4.15 x 6,261 ops/sec ±0.22% (100 runs sampled)
decode: sourcemap-codec x 4,472 ops/sec ±0.90% (99 runs sampled)
decode: source-map-0.6.1 x 449 ops/sec ±0.31% (95 runs sampled)
decode: source-map-0.8.0 x 3,219 ops/sec ±0.13% (100 runs sampled)
chrome dev tools x 1,743 ops/sec ±0.20% (99 runs sampled)
Fastest is decode: @jridgewell/sourcemap-codec 1.4.15

Encode Memory Usage:
local code                              140960 bytes
@jridgewell/sourcemap-codec 1.4.15      159808 bytes
sourcemap-codec                         969304 bytes
source-map-0.6.1                        930520 bytes
source-map-0.8.0                        930248 bytes
Smallest memory usage is local code

Encode speed:
encode: local code x 8,013 ops/sec ±0.19% (100 runs sampled)
encode: @jridgewell/sourcemap-codec 1.4.15 x 7,989 ops/sec ±0.20% (101 runs sampled)
encode: sourcemap-codec x 2,472 ops/sec ±0.21% (99 runs sampled)
encode: source-map-0.6.1 x 2,200 ops/sec ±0.17% (99 runs sampled)
encode: source-map-0.8.0 x 2,220 ops/sec ±0.37% (99 runs sampled)
Fastest is encode: local code


***


vscode.map - 2141001 segments

Decode Memory Usage:
local code                           198955264 bytes
@jridgewell/sourcemap-codec 1.4.15   199175352 bytes
sourcemap-codec                      199102688 bytes
source-map-0.6.1                     386323432 bytes
source-map-0.8.0                     244116432 bytes
chrome dev tools                     293734280 bytes
Smallest memory usage is local code

Decode speed:
decode: local code x 3.90 ops/sec ±22.21% (15 runs sampled)
decode: @jridgewell/sourcemap-codec 1.4.15 x 3.95 ops/sec ±23.53% (15 runs sampled)
decode: sourcemap-codec x 3.82 ops/sec ±17.94% (14 runs sampled)
decode: source-map-0.6.1 x 0.61 ops/sec ±7.81% (6 runs sampled)
decode: source-map-0.8.0 x 9.54 ops/sec ±0.28% (28 runs sampled)
chrome dev tools x 2.18 ops/sec ±10.58% (10 runs sampled)
Fastest is decode: source-map-0.8.0

Encode Memory Usage:
local code                            13509880 bytes
@jridgewell/sourcemap-codec 1.4.15    13537648 bytes
sourcemap-codec                       32540104 bytes
source-map-0.6.1                     127531040 bytes
source-map-0.8.0                     127535312 bytes
Smallest memory usage is local code

Encode speed:
encode: local code x 20.10 ops/sec ±0.19% (38 runs sampled)
encode: @jridgewell/sourcemap-codec 1.4.15 x 20.26 ops/sec ±0.32% (38 runs sampled)
encode: sourcemap-codec x 5.44 ops/sec ±1.64% (18 runs sampled)
encode: source-map-0.6.1 x 2.30 ops/sec ±4.79% (10 runs sampled)
encode: source-map-0.8.0 x 2.46 ops/sec ±6.53% (10 runs sampled)
Fastest is encode: @jridgewell/sourcemap-codec 1.4.15

License

MIT