231 lines
8.7 KiB
Markdown
231 lines
8.7 KiB
Markdown
Overview [](https://travis-ci.org/lydell/source-map-resolve)
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========
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Resolve the source map and/or sources for a generated file.
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```js
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var sourceMapResolve = require("source-map-resolve")
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var sourceMap = require("source-map")
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var code = [
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"!function(){...}();",
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"/*# sourceMappingURL=foo.js.map */"
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].join("\n")
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sourceMapResolve.resolveSourceMap(code, "/js/foo.js", fs.readFile, function(error, result) {
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if (error) {
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return notifyFailure(error)
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}
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result
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// {
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// map: {file: "foo.js", mappings: "...", sources: ["/coffee/foo.coffee"], names: []},
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// url: "/js/foo.js.map",
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// sourcesRelativeTo: "/js/foo.js.map",
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// sourceMappingURL: "foo.js.map"
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// }
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sourceMapResolve.resolveSources(result.map, result.sourcesRelativeTo, fs.readFile, function(error, result) {
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if (error) {
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return notifyFailure(error)
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}
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result
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// {
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// sourcesResolved: ["/coffee/foo.coffee"],
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// sourcesContent: ["<contents of /coffee/foo.coffee>"]
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// }
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})
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})
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sourceMapResolve.resolve(code, "/js/foo.js", fs.readFile, function(error, result) {
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if (error) {
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return notifyFailure(error)
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}
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result
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// {
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// map: {file: "foo.js", mappings: "...", sources: ["/coffee/foo.coffee"], names: []},
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// url: "/js/foo.js.map",
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// sourcesRelativeTo: "/js/foo.js.map",
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// sourceMappingURL: "foo.js.map",
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// sourcesResolved: ["/coffee/foo.coffee"],
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// sourcesContent: ["<contents of /coffee/foo.coffee>"]
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// }
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result.map.sourcesContent = result.sourcesContent
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var map = new sourceMap.sourceMapConsumer(result.map)
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map.sourceContentFor("/coffee/foo.coffee")
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// "<contents of /coffee/foo.coffee>"
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})
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```
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Installation
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============
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- `npm install source-map-resolve`
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- `bower install source-map-resolve`
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- `component install lydell/source-map-resolve`
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Works with CommonJS, AMD and browser globals, through UMD.
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Note: This module requires `setImmediate` and `atob`.
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Use polyfills if needed, such as:
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- <https://github.com/NobleJS/setImmediate>
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- <https://github.com/davidchambers/Base64.js>
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Usage
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=====
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### `sourceMapResolve.resolveSourceMap(code, codeUrl, read, callback)` ###
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- `code` is a string of code that may or may not contain a sourceMappingURL
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comment. Such a comment is used to resolve the source map.
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- `codeUrl` is the url to the file containing `code`. If the sourceMappingURL
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is relative, it is resolved against `codeUrl`.
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- `read(url, callback)` is a function that reads `url` and responds using
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`callback(error, content)`. In Node.js you might want to use `fs.readFile`,
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while in the browser you might want to use an asynchronus `XMLHttpRequest`.
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- `callback(error, result)` is a function that is invoked with either an error
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or `null` and the result.
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The result is an object with the following properties:
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- `map`: The source map for `code`, as an object (not a string).
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- `url`: The url to the source map. If the source map came from a data uri,
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this property is `null`, since then there is no url to it.
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- `sourcesRelativeTo`: The url that the sources of the source map are relative
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to. Since the sources are relative to the source map, and the url to the
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source map is provided as the `url` property, this property might seem
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superfluos. However, remember that the `url` property can be `null` if the
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source map came from a data uri. If so, the sources are relative to the file
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containing the data uri—`codeUrl`. This property will be identical to the
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`url` property or `codeUrl`, whichever is appropriate. This way you can
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conveniently resolve the sources without having to think about where the
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source map came from.
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- `sourceMappingURL`: The url of the sourceMappingURL comment in `code`.
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If `code` contains no sourceMappingURL, the result is `null`.
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### `sourceMapResolve.resolveSources(map, mapUrl, read, [options], callback)` ###
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- `map` is a source map, as an object (not a string).
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- `mapUrl` is the url to the file containing `map`. Relative sources in the
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source map, if any, are resolved against `mapUrl`.
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- `read(url, callback)` is a function that reads `url` and responds using
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`callback(error, content)`. In Node.js you might want to use `fs.readFile`,
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while in the browser you might want to use an asynchronus `XMLHttpRequest`.
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- `options` is an optional object with any of the following properties:
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- `sourceRoot`: Override the `sourceRoot` property of the source map, which
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might only be relevant when resolving sources in the browser. This lets you
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bypass it when using the module outside of a browser, if needed. Pass a
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string to replace the `sourceRoot` property with, or `false` to ignore it.
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Defaults to `undefined`.
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- `callback(error, result)` is a function that is invoked with either an error
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or `null` and the result.
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The result is an object with the following properties:
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- `sourcesResolved`: The same as `map.sources`, except all the sources are
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fully resolved.
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- `sourcesContent`: An array with the contents of all sources in `map.sources`,
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in the same order as `map.sources`. If getting the contents of a source fails,
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an error object is put into the array instead.
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### `sourceMapResolve.resolve(code, codeUrl, read, [options], callback)` ###
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The arguments are identical to `sourceMapResolve.resolveSourceMap`, except that
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you may also provide the same `options` as in `sourceMapResolve.resolveSources`.
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This is a convenience method that first resolves the source map and then its
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sources. You could also do this by first calling
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`sourceMapResolve.resolveSourceMap` and then `sourceMapResolve.resolveSources`.
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The result is identical to `sourceMapResolve.resolveSourceMap`, with the
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properties from `sourceMapResolve.resolveSources` merged into it.
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There is one extra feature available, though. If `code` is `null`, `codeUrl` is
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treated as a url to the source map instead of to `code`, and will be read. This
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is handy if you _sometimes_ get the source map url from the `SourceMap: <url>`
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header (see the [Notes] section). In this case, the `sourceMappingURL` property
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of the result is `null`.
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[Notes]: #notes
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### `sourceMapResolve.*Sync()` ###
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There are also sync versions of the three previous functions. They are identical
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to the async versions, except:
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- They expect a sync reading function. In Node.js you might want to use
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`fs.readFileSync`, while in the browser you might want to use a synchronus
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`XMLHttpRequest`.
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- They throw errors and return the result instead of using a callback.
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`sourceMapResolve.resolveSourcesSync` also accepts `null` as the `read`
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parameter. The result is the same as when passing a function as the `read
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parameter`, except that the `sourcesContent` property of the result will be an
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empty array. In other words, the sources aren’t read. You only get the
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`sourcesResolved` property. (This only supported in the synchronus version, since
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there is no point doing it asynchronusly.)
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### `sourceMapResolve.parseMapToJSON(string, [data])` ###
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The spec says that if a source map (as a string) starts with `)]}'`, it should
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be stripped off. This is to prevent XSSI attacks. This function does that and
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returns the result of `JSON.parse`ing what’s left.
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If this function throws `error`, `error.sourceMapData === data`.
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### Errors
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All errors passed to callbacks or thrown by this module have a `sourceMapData`
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property that contain as much as possible of the intended result of the function
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up until the error occurred.
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Note that while the `map` property of result objects always is an object,
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`error.sourceMapData.map` will be a string if parsing that string fails.
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Note
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====
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This module resolves the source map for a given generated file by looking for a
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sourceMappingURL comment. The spec defines yet a way to provide the URL to the
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source map: By sending the `SourceMap: <url>` header along with the generated
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file. Since this module doesn’t retrive the generated code for you (instead
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_you_ give the generated code to the module), it’s up to you to look for such a
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header when you retrieve the file (should the need arise).
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Development
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===========
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Tests
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-----
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First off, run `npm install` to install testing modules and browser polyfills.
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`npm test` lints the code and runs the test suite in Node.js.
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x-package.json5
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---------------
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package.json, component.json and bower.json are all generated from
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x-package.json5 by using [`xpkg`]. Only edit x-package.json5, and remember to
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run `xpkg` before commiting!
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[`xpkg`]: https://github.com/kof/node-xpkg
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Generating the browser version
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------------------------------
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source-map-resolve.js is generated from source-map-resolve-node.js and
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source-map-resolve-template.js. Only edit the two latter files, _not_
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source-map-resolve.js! To generate it, run `npm run build`.
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License
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=======
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[The X11 (“MIT”) License](LICENSE).
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