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+# 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