chrome-devtools-frontend
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Chrome DevTools UI
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# source-map-scopes-codec [](https://jsr.io/@chrome-devtools/source-map-scopes-codec)
This library hosts a production ready implementation of the source map ["Scopes" proposal](https://github.com/tc39/ecma426/blob/main/proposals/scopes.md).
The library contains:
* Type definitions for structured scope information
* Encode and decode functions that can encode structured scope information into an already existing source map, or decode the structured scope information from a source map.
* A builder that helps with building the structured scope information.
This library doesn't implement mappings encoding/decoding, but it does support encoding the scopes information into an already existing source map with "mappings" and "names".
## Installation
With NPM:
```sh
npx jsr add @chrome-devtools/source-map-scopes-codec
```
## Usage
Using the library is straight-forward:
```js
import { encode } from "@chrome-devtools/source-map-scopes-codec";
const scopeInformation = ...;
const map = encode(scopeInformation);
// Or with a pre-existing source map.
const map = encode(scopeInformation, preExistingSourceMap);
```
To decode:
```js
import { decode } from "@chrome-devtools/source-map-scopes-codec";
const scopeInformation = decode(sourceMap);
```
### Scope Builder
The library also contains a builder that makes creating structured scope information easier:
```js
import { ScopeInfoBuilder } from "@chrome-devtools/source-map-scopes-codec";
const scopeInformation = new ScopeInfoBuilder()
.startScope(0, 0, { kind: "Global" })
.startScope(5, 10)
.setScopeKind("Function") // Same as passing 'kind' to 'startScope'.
.setScopeName("foo") // Same as passing 'name' to 'startScope'.
.endScope(10, 5)
.endScope(11, 1)
.startRange(0, 0, { scope: 0 })
.startRange(0, 10)
.setRangeScopeDefinition(1) // Same as passing 'scope' to 'startRange'.
.endRange(0, 15)
.endRange(1, 1)
.build();
```
There is also a `SafeScopeInfoBuilder` that checks that scopes and ranges are well nested and some other integrity constraints (e.g. definition scopes are known).