# CSS Selector Generator JavaScript library for creating CSS selectors for a given DOM element or multiple DOM elements. See the [benchmark](https://fczbkk.github.io/css-selector-generator-benchmark/) to compare the speed and features of CSS Selector Generator with similar libraries. ## Table of Contents - [Install](#install) - [How to use](#how-to-use) - [Usage without NPM](#usage-without-npm) - [Usage with virtual DOM (e.g. JSDOM)](#usage-with-virtual-dom-eg-jsdom) - [Shadow DOM](#shadow-dom) - [TypeScript](#typescript) - [Multi-element selector](#multi-element-selector) - [Fallback](#fallback) - [Options](#options) - [Selector types](#selector-types) - [Root element](#root-element) - [Blacklist](#blacklist) - [Whitelist](#whitelist) - [Ignore generated class names](#ignore-generated-class-names) - [Combine within selector](#combine-within-selector) - [Combine between selectors](#combine-between-selectors) - [Include tag](#include-tag) - [Max combinations](#max-combinations) - [Max candidates](#max-candidates) - [Max results](#max-results) - [Use scope](#use-scope) - [Bug reports, feature requests and contact](#bug-reports-feature-requests-and-contact) - [License](#license) ## Try it You can try the library in the [sandbox](https://fczbkk.github.io/css-selector-generator-sandbox/) - write HTML code and see what CSS selectors the library produces. ## Install Add the library to your project via NPM or Yarn. ```shell npm install css-selector-generator # or yarn add css-selector-generator ``` Then include it in your source code: ```javascript import { getCssSelector, cssSelectorGenerator } from "css-selector-generator"; ``` ## How to use Simplest way to use it is to provide an element reference, without any options. ```html

``` You can use either `getCssSelector` function that returns the first found selector: ```javascript getCssSelector(targetElement); // ".myElement" ``` Or you can use `cssSelectorGenerator` function that returns a generator yielding all possible selectors, starting from the simplest ones, ending with the fallback selector: ```javascript [...cssSelectorGenerator(targetElement)]; // [".myElement", "div.myElement", "body .myElement"] ``` You can set options using second parameter for both functions. The options are described in the [Options](#options) section. ```javascript getCssSelector(targetElement, { includeTag: true }); // "div.myElement" [...cssSelectorGenerator(targetElement, { maxResults: 2 })]; // [".myElement", "div.myElement"] ``` Typical example is to create a selector for any element that the user clicks on: ```javascript // track every click document.body.addEventListener("click", function (event) { // get reference to the element user clicked on const element = event.target; // get unique CSS selector for that element const selector = getCssSelector(element); // do whatever you need to do with that selector console.log("selector", selector); }); ``` ### Usage without NPM If you don't want to use this library with NPM, you can download it from the "build" folder and insert it to your HTML document directly. In this case, the library is wrapped in namespace `CssSelectorGenerator`. So the usage would look something like this: ```html ``` ### Usage with virtual DOM (e.g. JSDOM) If you want to use this library with Node, usually for testing, don't require it directly into the Node process. It will not work, because there's no `window` object and there are no elements to select. Instead, you have to add the library to the virtual `window` object. Here are instructions how to do it in JSDOM, other libraries will work in a similar way: https://github.com/jsdom/jsdom/wiki/Don't-stuff-jsdom-globals-onto-the-Node-global ### Shadow DOM This library supports generating selectors for elements within shadow DOM. When you provide an element that is part of a shadow DOM tree, the library will automatically infer the shadow root and generate a selector relative to it. ```javascript const shadowRoot = element.attachShadow({ mode: "open" }); const shadowElement = shadowRoot.appendChild(document.createElement("div")); shadowElement.className = "shadowElement"; // Automatically detects shadow root getCssSelector(shadowElement); // ".shadowElement" // Or explicitly specify the shadow root getCssSelector(shadowElement, { root: shadowRoot }); // ".shadowElement" ``` ### TypeScript This library is written in TypeScript and includes type definitions. You can import the types directly: ```typescript import { getCssSelector, cssSelectorGenerator } from "css-selector-generator"; import type { CssSelectorGeneratorOptionsInput, CssSelectorType, } from "css-selector-generator/types/types.js"; const options: CssSelectorGeneratorOptionsInput = { selectors: ["class", "id", "tag"], blacklist: [".ignore-*"], root: document.body, }; const selector = getCssSelector(targetElement, options); ``` ### Multi-element selector This library also allows you to create selector targeting multiple elements at once. You do that by calling the same function, but you provide an array of elements instead of single element: ```html

``` ```javascript getCssSelector([firstElement, secondElement]); // ".bbb" ``` If it is not possible to construct single selector for all elements a standalone selector for each element will be generated: ```html

``` ```javascript getCssSelector([firstElement, secondElement]); // "div, span" ``` ### Fallback `getCssSelector` determines the shortest CSS selector for parent -> child relationship, from the input Element until the Root Element. If there is no _unique_ selector available for any of these relationships (parent -> child), a fallback of `*` will be used for this relationship. #wrapper > * > div > .text In some cases, this selector may not be unique (e.g. `#wrapper > * > div > *`). In this case, it will fall back to an entire chain of `:nth-child` selectors like: ":nth-child(2) > :nth-child(4) > :nth-child(1) > :nth-child(12)" ## Options - [`selectors`](#selector-types) - [`root`](#root-element) - [`blacklist`](#blacklist) - [`whitelist`](#whitelist) - [`ignoreGeneratedClassNames`](#ignore-generated-class-names) - [`combineWithinSelector`](#combine-within-selector) - [`combineBetweenSelectors`](#combine-between-selectors) - [`includeTag`](#include-tag) - [`maxCombinations`](#max-combinations) - [`maxCandidates`](#max-candidates) - [`maxResults`](#max-results) _(only applicable in `cssSelectorGenerator`)_ - [`useScope`](#use-scope) ### Selector types You can choose which types of selectors do you want to use: ```html

``` ```javascript getCssSelector(targetElement, { selectors: ["class"] }); // ".myElement" getCssSelector(targetElement, { selectors: ["tag"] }); // "div" ``` Order of selector types defines their priority: ```javascript getCssSelector(targetElement, { selectors: ["class", "tag"] }); // ".myElement" getCssSelector(targetElement, { selectors: ["tag", "class"] }); // "div" ``` Valid selector types are: - `id` - `class` - `tag` - `attribute` - `nthchild` - `nthoftype` ### Root element You can define root element, from which the selector will be created. If root element is not defined, document root will be used: ```html

``` ```javascript getCssSelector(targetElement); // ".myRootElement > .myElement" getCssSelector(targetElement, { root: document.querySelector(".myRootElement"), }); // ".myElement" ``` ### Blacklist If you want to ignore some selectors, you can put them on the blacklist. Blacklist is an array that can contain either regular expressions, strings and/or functions. In **strings**, you can use an asterisk (`*`) as a wildcard that will match any number of any characters. **Functions** will receive a selector as a parameter. They should always return boolean, `true` if it is a match, `false` if it is not. Any other type of return value will be ignored. ```html

``` ```javascript getCssSelector(targetElement, { blacklist: [".firstClass"] }); // ".secondClass" getCssSelector(targetElement, { blacklist: [".first*"] }); // ".secondClass" getCssSelector(targetElement, { blacklist: [/first/] }); // ".secondClass" getCssSelector(targetElement, { blacklist: [(input) => input.startsWith(".first")], }); // ".secondClass" ``` You can target selectors of any types using the blacklist. ```javascript getCssSelector(targetElement, { blacklist: [ // ID selector "#forbiddenId", // class selector ".forbiddenClass", // attribute selector "[forbidden-attribute]", // tag selector "div", ], }); ``` ### Whitelist Same as `blacklist` option, but instead of ignoring matching selectors, they will be prioritised. ```html

``` ```javascript getCssSelector(targetElement, { whitelist: [".secondClass"] }); // ".secondClass" getCssSelector(targetElement, { whitelist: [".second*"] }); // ".secondClass" getCssSelector(targetElement, { whitelist: [/second/] }); // ".secondClass" ``` ### Ignore generated class names If set to `true`, the generator will ignore class names that appear to be generated by CSS-in-JS libraries (e.g., Emotion, styled-components, MUI). This is useful when working with modern React applications that use CSS-in-JS, as these generated class names are not stable and change between builds. ```html

``` ```javascript getCssSelector(targetElement, { ignoreGeneratedClassNames: false }); // ".css-1x2y3z" - uses the generated class name (default behavior) getCssSelector(targetElement, { ignoreGeneratedClassNames: true }); // ".button-primary" - ignores generated class, uses human-readable one ``` The option uses heuristics to detect generated class names: - Rejects common CSS-in-JS library prefixes (e.g., `css-`, `sc-`, `emotion-`, `makeStyles-`) - Rejects class names with patterns that don't look like human-written names - Preserves word-like class names (e.g., `button`, `nav-container`, `userProfile`, `block__element--modifier`) **Note:** The `whitelist` option takes precedence. If you whitelist a generated class name, it will be used even when `ignoreGeneratedClassNames` is enabled. ```javascript getCssSelector(targetElement, { ignoreGeneratedClassNames: true, whitelist: [".css-*"], // Whitelist overrides the filter }); // May use ".css-1x2y3z" if it's unique ``` If the built-in heuristic doesn't work for your use case, you can achieve similar functionality using the `blacklist` option with a custom function: ```javascript getCssSelector(targetElement, { blacklist: [ (className) => { // Your custom logic to detect generated classes return /^(css-|sc-|makeStyles-)/.test(className); }, ], }); ``` ### Combine within selector If set to `true`, the generator will try to look for combinations of selectors within a single type (usually class names) to get better overall selector. ```html

``` ```javascript getCssSelector(targetElement, { combineWithinSelector: false }); // "body > :nth-child(1)" - in this case no single class name is unique getCssSelector(targetElement, { combineWithinSelector: true }); // ".aaa.bbb" ``` This option is set to `true` by default. It can be set to `false` for performance reasons. ### Combine between selectors If set to `true`, the generator will try to look for combinations of selectors between various types (e.g. tag name + class name) to get better overall selector. ```html

``` ```javascript getCssSelector(targetElement, { combineBetweenSelectors: false }); // "body > :nth-child(1)" - in this case no single class name or tag name is unique getCssSelector(targetElement, { combineBetweenSelectors: true }); // "div.aaa" ``` This option is set to `true` by default. It can be set to `false` for performance reasons. ### Include tag This option will add tag selector type to every selector: ```html

``` ```javascript getCssSelector(targetElement, { includeTag: true }); // "div.myElement" ``` ### Max combinations This is a performance optimization option that can help when trying to find a CSS selector within elements that contain large numbers of class names (e.g. because of frameworks that create atomic styles) or other attributes. In such case, the number of possible combinations between class names can be too large (it grows exponentially) and can significantly slow down selector generation. In reality, if the selector is not found within first few combinations, it usually won't be found within the rest of combinations. ```javascript getCssSelector(targetElement, { maxCombinations: 100 }); ``` ### Max candidates Performance optimization option, similar to `maxCombinations`. This does limit a total number of selector candidates for each element. You should use it in cases, when there are not too many class names and attributes, but they are numerous enough to produce large number of combinations between them. ```javascript getCssSelector(targetElement, { maxCandidates: 100 }); ``` ### Max results _Only applicable in the `cssSelectorGenerator()`. Not in the `getCssSelector()` function._ Limits the maximum number of yielded selectors. By default, all possible selectors are yielded, starting from the simplest ones, ending with the fallback selector. In some cases, this may produce a very large number of selectors. To prevent performance issues, you should set a limit to the number of results. You can also use it to get multiple selector options, so you can choose the one you like the most. Let's say you have the following HTML code: ```html

``` This will produce 2^n selectors, where n is the number of classes in the element (in case the class names produce unique selectors). The number of possible combinations grows exponentially: ```javascript const allSelectors = [ ...cssSelectorGenerator(needleElement, { selectors: ["class"] }), ]; // [".aaa", ".bbb", ".ccc", ".aaa.bbb", ".aaa.ccc", ".bbb.ccc", ".aaa.bbb.ccc"] ``` That's why it's a good idea to limit the maximum number of results. Besides, their quality tends to decrease with the increasing complexity. ```javascript const fewSelectors = [ ...cssSelectorGenerator(needleElement, { selectors: ["class"], maxResults: 5, }), ]; // [".aaa", ".bbb", ".ccc", ".aaa.bbb", ".aaa.ccc"] ``` ### Use scope **Experimental feature** - _This will probably be turned on by default and the option will be removed, after I thoroughly evaluate that it produces valid selectors in all use cases._ If set to `true` and the [`root` option](#root-element) is provided, the fallback selectors will be created relative to the `root` element using the `:scope` pseudo-class. For example, if you have the following HTML structure: ```html

``` If you generate the selector **without** the `useScope` option: ```javascript getCssSelector(needleElement, { root: haystackElement, useScope: false, }); ``` ...it will produce this fallback selector: ``` :root > :nth-child(1) > :nth-child(1) > :nth-child(1) > :nth-child(1) > :nth-child(1) ``` ... where the selectors correspond with these elements: ``` :root -> > :nth-child(1) -> > :nth-child(1) ->

> :nth-child(1) ->

``` But if you generate the selector **with** the `useScope` option: ```javascript getCssSelector(needleElement, { root: haystackElement, useScope: true, }); ``` ...it will produce this fallback selector: `:scope > :nth-child(1) > :nth-child(1)` ... where the selectors correspond with these elements: ``` :scope ->

> :nth-child(1) ->

``` ## Bug reports, feature requests and contact If you found any bugs, if you have feature requests or any questions, please, either [file an issue on GitHub][1] or send me an e-mail at [riki@fczbkk.com][2] ## License CSS Selector Generator is published under the [MIT license][3]. [1]: https://github.com/fczbkk/css-selector-generator/issues [2]: mailto:riki@fczbkk.com?subject=CSSSelectorGenerator [3]: https://github.com/fczbkk/css-selector-generator/blob/master/LICENSE