# convert-source-map [![Build Status][ci-image]][ci-url]
Converts a source-map from/to different formats and allows adding/changing properties.
```js
var convert = require('convert-source-map');
var json = convert
.fromComment('//# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJmaWxlIjoiYnVpbGQvZm9vLm1pbi5qcyIsInNvdXJjZXMiOlsic3JjL2Zvby5qcyJdLCJuYW1lcyI6W10sIm1hcHBpbmdzIjoiQUFBQSIsInNvdXJjZVJvb3QiOiIvIn0=')
.toJSON();
var modified = convert
.fromComment('//# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJmaWxlIjoiYnVpbGQvZm9vLm1pbi5qcyIsInNvdXJjZXMiOlsic3JjL2Zvby5qcyJdLCJuYW1lcyI6W10sIm1hcHBpbmdzIjoiQUFBQSIsInNvdXJjZVJvb3QiOiIvIn0=')
.setProperty('sources', [ 'SRC/FOO.JS' ])
.toJSON();
console.log(json);
console.log(modified);
```
```json
{"version":3,"file":"build/foo.min.js","sources":["src/foo.js"],"names":[],"mappings":"AAAA","sourceRoot":"/"}
{"version":3,"file":"build/foo.min.js","sources":["SRC/FOO.JS"],"names":[],"mappings":"AAAA","sourceRoot":"/"}
```
## Upgrading
Prior to v2.0.0, the `fromMapFileComment` and `fromMapFileSource` functions took a String directory path and used that to resolve & read the source map file from the filesystem. However, this made the library limited to nodejs environments and broke on sources with querystrings.
In v2.0.0, you now need to pass a function that does the file reading. It will receive the source filename as a String that you can resolve to a filesystem path, URL, or anything else.
If you are using `convert-source-map` in nodejs and want the previous behavior, you'll use a function like such:
```diff
+ var fs = require('fs'); // Import the fs module to read a file
+ var path = require('path'); // Import the path module to resolve a path against your directory
- var conv = convert.fromMapFileSource(css, '../my-dir');
+ var conv = convert.fromMapFileSource(css, function (filename) {
+ return fs.readFileSync(path.resolve('../my-dir', filename), 'utf-8');
+ });
```
## API
### fromObject(obj)
Returns source map converter from given object.
### fromJSON(json)
Returns source map converter from given json string.
### fromURI(uri)
Returns source map converter from given uri encoded json string.
### fromBase64(base64)
Returns source map converter from given base64 encoded json string.
### fromComment(comment)
Returns source map converter from given base64 or uri encoded json string prefixed with `//# sourceMappingURL=...`.
### fromMapFileComment(comment, readMap)
Returns source map converter from given `filename` by parsing `//# sourceMappingURL=filename`.
`readMap` must be a function which receives the source map filename and returns either a String or Buffer of the source map (if read synchronously), or a `Promise` containing a String or Buffer of the source map (if read asynchronously).
If `readMap` doesn't return a `Promise`, `fromMapFileComment` will return a source map converter synchronously.
If `readMap` returns a `Promise`, `fromMapFileComment` will also return `Promise`. The `Promise` will be either resolved with the source map converter or rejected with an error.
#### Examples
**Synchronous read in Node.js:**
```js
var convert = require('convert-source-map');
var fs = require('fs');
function readMap(filename) {
return fs.readFileSync(filename, 'utf8');
}
var json = convert
.fromMapFileComment('//# sourceMappingURL=map-file-comment.css.map', readMap)
.toJSON();
console.log(json);
```
**Asynchronous read in Node.js:**
```js
var convert = require('convert-source-map');
var { promises: fs } = require('fs'); // Notice the `promises` import
function readMap(filename) {
return fs.readFile(filename, 'utf8');
}
var converter = await convert.fromMapFileComment('//# sourceMappingURL=map-file-comment.css.map', readMap)
var json = converter.toJSON();
console.log(json);
```
**Asynchronous read in the browser:**
```js
var convert = require('convert-source-map');
async function readMap(url) {
const res = await fetch(url);
return res.text();
}
const converter = await convert.fromMapFileComment('//# sourceMappingURL=map-file-comment.css.map', readMap)
var json = converter.toJSON();
console.log(json);
```
### fromSource(source)
Finds last sourcemap comment in file and returns source map converter or returns `null` if no source map comment was found.
### fromMapFileSource(source, readMap)
Finds last sourcemap comment in file and returns source map converter or returns `null` if no source map comment was found.
`readMap` must be a function which receives the source map filename and returns either a String or Buffer of the source map (if read synchronously), or a `Promise` containing a String or Buffer of the source map (if read asynchronously).
If `readMap` doesn't return a `Promise`, `fromMapFileSource` will return a source map converter synchronously.
If `readMap` returns a `Promise`, `fromMapFileSource` will also return `Promise`. The `Promise` will be either resolved with the source map converter or rejected with an error.
### toObject()
Returns a copy of the underlying source map.
### toJSON([space])
Converts source map to json string. If `space` is given (optional), this will be passed to
[JSON.stringify](https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/JSON/stringify) when the
JSON string is generated.
### toURI()
Converts source map to uri encoded json string.
### toBase64()
Converts source map to base64 encoded json string.
### toComment([options])
Converts source map to an inline comment that can be appended to the source-file.
By default, the comment is formatted like: `//# sourceMappingURL=...`, which you would
normally see in a JS source file.
When `options.encoding == 'uri'`, the data will be uri encoded, otherwise they will be base64 encoded.
When `options.multiline == true`, the comment is formatted like: `/*# sourceMappingURL=... */`, which you would find in a CSS source file.
### addProperty(key, value)
Adds given property to the source map. Throws an error if property already exists.
### setProperty(key, value)
Sets given property to the source map. If property doesn't exist it is added, otherwise its value is updated.
### getProperty(key)
Gets given property of the source map.
### removeComments(src)
Returns `src` with all source map comments removed
### removeMapFileComments(src)
Returns `src` with all source map comments pointing to map files removed.
### commentRegex
Provides __a fresh__ RegExp each time it is accessed. Can be used to find source map comments.
Breaks down a source map comment into groups: Groups: 1: media type, 2: MIME type, 3: charset, 4: encoding, 5: data.
### mapFileCommentRegex
Provides __a fresh__ RegExp each time it is accessed. Can be used to find source map comments pointing to map files.
### generateMapFileComment(file, [options])
Returns a comment that links to an external source map via `file`.
By default, the comment is formatted like: `//# sourceMappingURL=...`, which you would normally see in a JS source file.
When `options.multiline == true`, the comment is formatted like: `/*# sourceMappingURL=... */`, which you would find in a CSS source file.
[ci-url]: https://github.com/thlorenz/convert-source-map/actions?query=workflow:ci
[ci-image]: https://img.shields.io/github/workflow/status/thlorenz/convert-source-map/CI?style=flat-square
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