1--- 2title: Dependency Selector Syntax & Querying 3section: 7 4description: Dependency Selector Syntax & Querying 5--- 6 7### Description 8 9The [`npm query`](/commands/npm-query) command exposes a new dependency selector syntax (informed by & respecting many aspects of the [CSS Selectors 4 Spec](https://dev.w3.org/csswg/selectors4/#relational)) which: 10 11- Standardizes the shape of, & querying of, dependency graphs with a robust object model, metadata & selector syntax 12- Leverages existing, known language syntax & operators from CSS to make disparate package information broadly accessible 13- Unlocks the ability to answer complex, multi-faceted questions about dependencies, their relationships & associative metadata 14- Consolidates redundant logic of similar query commands in `npm` (ex. `npm fund`, `npm ls`, `npm outdated`, `npm audit` ...) 15 16### Dependency Selector Syntax 17 18#### Overview: 19 20- there is no "type" or "tag" selectors (ex. `div, h1, a`) as a dependency/target is the only type of `Node` that can be queried 21- the term "dependencies" is in reference to any `Node` found in a `tree` returned by `Arborist` 22 23#### Combinators 24 25- `>` direct descendant/child 26- ` ` any descendant/child 27- `~` sibling 28 29#### Selectors 30 31- `*` universal selector 32- `#<name>` dependency selector (equivalent to `[name="..."]`) 33- `#<name>@<version>` (equivalent to `[name=<name>]:semver(<version>)`) 34- `,` selector list delimiter 35- `.` dependency type selector 36- `:` pseudo selector 37 38#### Dependency Type Selectors 39 40- `.prod` dependency found in the `dependencies` section of `package.json`, or is a child of said dependency 41- `.dev` dependency found in the `devDependencies` section of `package.json`, or is a child of said dependency 42- `.optional` dependency found in the `optionalDependencies` section of `package.json`, or has `"optional": true` set in its entry in the `peerDependenciesMeta` section of `package.json`, or a child of said dependency 43- `.peer` dependency found in the `peerDependencies` section of `package.json` 44- `.workspace` dependency found in the [`workspaces`](https://docs.npmjs.com/cli/v8/using-npm/workspaces) section of `package.json` 45- `.bundled` dependency found in the `bundleDependencies` section of `package.json`, or is a child of said dependency 46 47#### Pseudo Selectors 48- [`:not(<selector>)`](https://developer.mozilla.org/en-US/docs/Web/CSS/:not) 49- [`:has(<selector>)`](https://developer.mozilla.org/en-US/docs/Web/CSS/:has) 50- [`:is(<selector list>)`](https://developer.mozilla.org/en-US/docs/Web/CSS/:is) 51- [`:root`](https://developer.mozilla.org/en-US/docs/Web/CSS/:root) matches the root node/dependency 52- [`:scope`](https://developer.mozilla.org/en-US/docs/Web/CSS/:scope) matches node/dependency it was queried against 53- [`:empty`](https://developer.mozilla.org/en-US/docs/Web/CSS/:empty) when a dependency has no dependencies 54- [`:private`](https://docs.npmjs.com/cli/v8/configuring-npm/package-json#private) when a dependency is private 55- `:link` when a dependency is linked (for instance, workspaces or packages manually [`linked`](https://docs.npmjs.com/cli/v8/commands/npm-link) 56- `:deduped` when a dependency has been deduped (note that this does *not* always mean the dependency has been hoisted to the root of node_modules) 57- `:overridden` when a dependency has been overridden 58- `:extraneous` when a dependency exists but is not defined as a dependency of any node 59- `:invalid` when a dependency version is out of its ancestors specified range 60- `:missing` when a dependency is not found on disk 61- `:semver(<spec>, [selector], [function])` match a valid [`node-semver`](https://github.com/npm/node-semver) version or range to a selector 62- `:path(<path>)` [glob](https://www.npmjs.com/package/glob) matching based on dependencies path relative to the project 63- `:type(<type>)` [based on currently recognized types](https://github.com/npm/npm-package-arg#result-object) 64- `:outdated(<type>)` when a dependency is outdated 65- `:vuln(<selector>)` when a dependency has a known vulnerability 66 67##### `:semver(<spec>, [selector], [function])` 68 69The `:semver()` pseudo selector allows comparing fields from each node's `package.json` using [semver](https://github.com/npm/node-semver#readme) methods. It accepts up to 3 parameters, all but the first of which are optional. 70 71- `spec` a semver version or range 72- `selector` an attribute selector for each node (default `[version]`) 73- `function` a semver method to apply, one of: `satisfies`, `intersects`, `subset`, `gt`, `gte`, `gtr`, `lt`, `lte`, `ltr`, `eq`, `neq` or the special function `infer` (default `infer`) 74 75When the special `infer` function is used the `spec` and the actual value from the node are compared. If both are versions, according to `semver.valid()`, `eq` is used. If both values are ranges, according to `!semver.valid()`, `intersects` is used. If the values are mixed types `satisfies` is used. 76 77Some examples: 78 79- `:semver(^1.0.0)` returns every node that has a `version` satisfied by the provided range `^1.0.0` 80- `:semver(16.0.0, :attr(engines, [node]))` returns every node which has an `engines.node` property satisfying the version `16.0.0` 81- `:semver(1.0.0, [version], lt)` every node with a `version` less than `1.0.0` 82 83##### `:outdated(<type>)` 84 85The `:outdated` pseudo selector retrieves data from the registry and returns information about which of your dependencies are outdated. The type parameter may be one of the following: 86 87- `any` (default) a version exists that is greater than the current one 88- `in-range` a version exists that is greater than the current one, and satisfies at least one if its parent's dependencies 89- `out-of-range` a version exists that is greater than the current one, does not satisfy at least one of its parent's dependencies 90- `major` a version exists that is a semver major greater than the current one 91- `minor` a version exists that is a semver minor greater than the current one 92- `patch` a version exists that is a semver patch greater than the current one 93 94In addition to the filtering performed by the pseudo selector, some extra data is added to the resulting objects. The following data can be found under the `queryContext` property of each node. 95 96- `versions` an array of every available version of the given node 97- `outdated.inRange` an array of objects, each with a `from` and `versions`, where `from` is the on-disk location of the node that depends on the current node and `versions` is an array of all available versions that satisfies that dependency. This is only populated if `:outdated(in-range)` is used. 98- `outdated.outOfRange` an array of objects, identical in shape to `inRange`, but where the `versions` array is every available version that does not satisfy the dependency. This is only populated if `:outdated(out-of-range)` is used. 99 100Some examples: 101 102- `:root > :outdated(major)` returns every direct dependency that has a new semver major release 103- `.prod:outdated(in-range)` returns production dependencies that have a new release that satisfies at least one of its parent's dependencies 104 105##### `:vuln` 106 107The `:vuln` pseudo selector retrieves data from the registry and returns information about which if your dependencies has a known vulnerability. Only dependencies whose current version matches a vulnerability will be returned. For example if you have `semver@7.6.0` in your tree, a vulnerability for `semver` which affects versions `<=6.3.1` will not match. 108 109You can also filter results by certain attributes in advisories. Currently that includes `severity` and `cwe`. Note that severity filtering is done per severity, it does not include severities "higher" or "lower" than the one specified. 110 111In addition to the filtering performed by the pseudo selector, info about each relevant advisory will be added to the `queryContext` attribute of each node under the `advisories` attribute. 112 113Some examples: 114 115- `:root > .prod:vuln` returns direct production dependencies with any known vulnerability 116- `:vuln([severity=high])` returns only dependencies with a vulnerability with a `high` severity. 117- `:vuln([severity=high],[severity=moderate])` returns only dependencies with a vulnerability with a `high` or `moderate` severity. 118- `:vuln([cwe=1333])` returns only dependencies with a vulnerability that includes CWE-1333 (ReDoS) 119 120#### [Attribute Selectors](https://developer.mozilla.org/en-US/docs/Web/CSS/Attribute_selectors) 121 122The attribute selector evaluates the key/value pairs in `package.json` if they are `String`s. 123 124- `[]` attribute selector (ie. existence of attribute) 125- `[attribute=value]` attribute value is equivalent... 126- `[attribute~=value]` attribute value contains word... 127- `[attribute*=value]` attribute value contains string... 128- `[attribute|=value]` attribute value is equal to or starts with... 129- `[attribute^=value]` attribute value starts with... 130- `[attribute$=value]` attribute value ends with... 131 132#### `Array` & `Object` Attribute Selectors 133 134The generic `:attr()` pseudo selector standardizes a pattern which can be used for attribute selection of `Object`s, `Array`s or `Arrays` of `Object`s accessible via `Arborist`'s `Node.package` metadata. This allows for iterative attribute selection beyond top-level `String` evaluation. The last argument passed to `:attr()` must be an `attribute` selector or a nested `:attr()`. See examples below: 135 136#### `Objects` 137 138```css 139/* return dependencies that have a `scripts.test` containing `"tap"` */ 140*:attr(scripts, [test~=tap]) 141``` 142 143#### Nested `Objects` 144 145Nested objects are expressed as sequential arguments to `:attr()`. 146 147```css 148/* return dependencies that have a testling config for opera browsers */ 149*:attr(testling, browsers, [~=opera]) 150``` 151 152#### `Arrays` 153 154`Array`s specifically uses a special/reserved `.` character in place of a typical attribute name. `Arrays` also support exact `value` matching when a `String` is passed to the selector. 155 156##### Example of an `Array` Attribute Selection: 157```css 158/* removes the distinction between properties & arrays */ 159/* ie. we'd have to check the property & iterate to match selection */ 160*:attr([keywords^=react]) 161*:attr(contributors, :attr([name~=Jordan])) 162``` 163 164##### Example of an `Array` matching directly to a value: 165```css 166/* return dependencies that have the exact keyword "react" */ 167/* this is equivalent to `*:keywords([value="react"])` */ 168*:attr([keywords=react]) 169``` 170 171##### Example of an `Array` of `Object`s: 172```css 173/* returns */ 174*:attr(contributors, [email=ruyadorno@github.com]) 175``` 176 177### Groups 178 179Dependency groups are defined by the package relationships to their ancestors (ie. the dependency types that are defined in `package.json`). This approach is user-centric as the ecosystem has been taught to think about dependencies in these groups first-and-foremost. Dependencies are allowed to be included in multiple groups (ex. a `prod` dependency may also be a `dev` dependency (in that it's also required by another `dev` dependency) & may also be `bundled` - a selector for that type of dependency would look like: `*.prod.dev.bundled`). 180 181- `.prod` 182- `.dev` 183- `.optional` 184- `.peer` 185- `.bundled` 186- `.workspace` 187 188Please note that currently `workspace` deps are always `prod` dependencies. Additionally the `.root` dependency is also considered a `prod` dependency. 189 190### Programmatic Usage 191 192- `Arborist`'s `Node` Class has a `.querySelectorAll()` method 193 - this method will return a filtered, flattened dependency Arborist `Node` list based on a valid query selector 194 195```js 196const Arborist = require('@npmcli/arborist') 197const arb = new Arborist({}) 198``` 199 200```js 201// root-level 202arb.loadActual().then(async (tree) => { 203 // query all production dependencies 204 const results = await tree.querySelectorAll('.prod') 205 console.log(results) 206}) 207``` 208 209```js 210// iterative 211arb.loadActual().then(async (tree) => { 212 // query for the deduped version of react 213 const results = await tree.querySelectorAll('#react:not(:deduped)') 214 // query the deduped react for git deps 215 const deps = await results[0].querySelectorAll(':type(git)') 216 console.log(deps) 217}) 218``` 219 220## See Also 221 222* [npm query](/commands/npm-query) 223* [@npmcli/arborist](https://npm.im/@npmcli/arborist) 224