finder

CSS Selector Generator

Features

• Generates shortest selectors
• Unique selectors per page
• Stable and robust selectors
• 2.1 kB gzip and minify size

Install

npm install @medv/finder

Finder can be used via modules:

<script type="module">
  import {finder} from 'https://medv.io/finder/finder.js'
</script>

Usage

import {finder} from '@medv/finder'

document.addEventListener('click', event => {
  const selector = finder(event.target)
  console.log(selector)  
})

Example

Example of generated selector:

.blog > article:nth-child(3) .add-comment

Configuration

finder takes configuration object as second parameters. Here is example of all params with default values:

const selector = finder(event.target, {
  root: document.body,
  className: (name) => true,
  tagName: (name) => true,
  attr: (name, value) => false,
  seedMinLength: 1,
  optimizedMinLength: 2,
  threshold: 1000,
  maxNumberOfTries: 10_000,
  maxRecursionDepth: 10,
})

root: Element

Root of search, defaults to document.body.

idName: (name: string) => boolean

Check if this ID can be used. For example you can restrict using framework specific IDs:

const selector = finder(event.target, {
  idName: name => !name.startsWith('ember')
})

className: (name: string) => boolean

Check if this class name can be used. For example you can restrict using is-* class names:

const selector = finder(event.target, {
  className: name => !name.startsWith('is-')
})

tagName: (name: string) => boolean

Check if tag name can be used, same as className.

attr: (name: string, value: string) => boolean

Check if attr name can be used.

seedMinLength: number

Minimum length of levels in fining selector. Starts from 1. For more robust selectors give this param value around 4-5 depending on depth of you DOM tree. If finder hits root this param is ignored.

optimizedMinLength: number

Minimum length for optimising selector. Starts from 2. For example selector body > div > div > p can be optimized to body p.

threshold: number

Max number of selectors to check before falling into nth-child usage. Checking for uniqueness of selector is very costs operation, if you have DOM tree depth of 5, with 5 classes on each level, that gives you more than 3k selectors to check. finder uses two step approach so it's reaching this threshold in some cases twice. Default 1000 is good enough in most cases.

maxNumberOfTries: number

Max number of tries when we do the optimization. It is a trade-off between optimization and efficiency. Default 10_000 is good enough in most cases.

maxRecursionDepth: number

Max recursion depth when generating selector combinations during search. Defaults to 10. For more complex DOM trees, generating these combinations can be very costly and can max out the CPU. Reducing this option will help in these cases because finder will throw an error instead when this depth has been exceeded.

Google Chrome Extension

Generate the unique selectors in your browser by using Chrome Extension

License

MIT