diff options
Diffstat (limited to 'node_modules/@jridgewell/sourcemap-codec/README.md')
-rw-r--r-- | node_modules/@jridgewell/sourcemap-codec/README.md | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/node_modules/@jridgewell/sourcemap-codec/README.md b/node_modules/@jridgewell/sourcemap-codec/README.md new file mode 100644 index 0000000..e4373aa --- /dev/null +++ b/node_modules/@jridgewell/sourcemap-codec/README.md @@ -0,0 +1,63 @@ +# sourcemap-codec + +Encode/decode the `mappings` property of a [sourcemap](https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit). + + +## 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](https://en.wikipedia.org/wiki/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 + +```bash +npm install sourcemap-codec +``` + + +## Usage + +```js +import { encode, decode } from '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' ); +``` + + +# License + +MIT |