mirror of
https://gitee.com/onvia/ccc-tnt-psd2ui
synced 2024-12-26 11:48:25 +00:00
64 lines
1.8 KiB
Markdown
64 lines
1.8 KiB
Markdown
|
# 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
|