lens

Create screenshots of your webpage in different resolutions in a matter of seconds.

By default, lens will generate screenshots for some common screen resolutions. You can find more info by exploring files in the src/viewports directory.

Prerequisites

• Node.js >= 14

Installation

npm install -g @magiczne/lens

yarn global add @magiczne/lens

Usage

lens --help
  
  Options:
        --help        Show help                                                                                  [boolean]
        --version     Show version number                                                                        [boolean]
    -u, --url         The url from which screenshots will be taken. If you want to create screenshots from multiple urls
                      separate them with a space (e.g. https://example.com https://example.com/page). Remember to include
                      protocol (http:// or https://)                                                               [array]
    -r, --resolution  Custom resolution (e.g. 800x600). If you want to create screenshots for multiple resolutions
                      separate them with a space (e.g. 800x600 1920x1080)                                          [array]
    -v, --viewports   Render screenshots only for selected viewport types
                                   [array] [choices: "desktop", "phone", "tablet"] [default: ["desktop","phone","tablet"]]
    -t, --tag         Custom tag that will be used as a subdirectory for screenshots                [string] [default: ""]
    -i, --input-dir   Input directory with screenshot rules                                                       [string]
    -o, --output-dir  Output directory for the screenshots                                                        [string]
                      
  Examples:
    lens -u https://example.com
    lens -u https://example.com -r 1280x720
    lens -u https://example.com https://example.com/subpage -r 1920x1080
    lens -u https://example.com -r 800x600 1280x720 -o ./output
    lens -u https://example.com -r 1280x720 -t "custom tag"
    lens -u https://example.com -v desktop phone

  For advanced usage documentation please visit https://github.com/Magiczne/lens

Advanced configuration

lens can be configured both locally and globally. When using lens globally, you can configure it in either a .lens.config.js or .lens.config.json located in your home directory. When using lens locally you can configure it using the same files, but located in your project root directory.

WARNING

If you pass -i or -o argument in the CLI the corresponding values from config files will be overridden!

Currently, these are options you can configure:

Option	Type	Default	Description
chunkSize	number	5	Number of screenshots to be taken at once. You can disable limit by putting 0 zero, but keep in mind it will consume your RAM.
directories.input	string	'./rules'	Input directory with rule files.
directories.output	string	'./screenshots'	Output directory for the screenshots.
puppeteer.headless	boolean	true	Whether to run browser in headless mode.
puppeteer.waitUntil	string | string[]	['load', 'networkidle2']	When to consider navigation succedeed. Refer to the puppeteer docs for detailed information.

Example config:

.lens.config.js

module.exports = {
    chunkSize: 10,
    directories: {
        input: './input',
        output: './output'
    },
    puppeteer: {
        headless: true,
        waitUntil: ['load', 'domcontentloaded', 'networkidle2']
    }
}

.lens.config.json

{
    "chunkSize": 10,
    "directories": {
        "input": "./input",
        "output": "./output"
    },
    "puppeteer": {
        "headless": true,
        "waitUntil": ["load", "domcontentloaded", "networkidle2"]
    }
}

Rule files

You can create rules file to create more than one set of screenshots at a time. Also, you can use afterPageLoaded hook to run some code before the screenshot will be taken. Look what you can do in the puppeteer Page class documentation.

If input directory contains more than one rule file, each one will be loaded and parsed.

Ruleset options

Option	Type	Default	Description
disable	boolean	false	If set to true screenshots for rules defined in this file will not be taken.
rules	array		required. Array of screenshot rules.

Rule options

Option	Type	Default	Description
url	string		required. The url from which screenshots will be taken.
tag	string		required. Custom tag that will be used as a subdirectory.
renderFor	array	['desktop', 'tablet', 'phone']	Array which can be: a list of keys which correspond to default viewports included with lens. Available values are 'desktop', 'tablet' or 'phone'. a set of custom puppeteer Viewports CAUTION! These options cannot be mixed. Rule parser will throw an error when you do like so.
afterPageLoaded	async function	undefined	Callback function which takes page as a parameter. It will be executed before the screenshot will be taken.

Example rules file

module.exports = {
    disable: true,
    rules: [
        // Simplest configuration
        {
            url: 'https://example.com',
            tag: 'few kittens'
        },
        
        // Exclude mobile viewports
        {
            url: 'https://example.com',
            tag: 'several kittens',
            renderFor: ['desktop', 'tablet']
        },
        
        // Specify custom set of viewports
        {
            url: 'https://example.com',
            tag: 'pack of kittens',
            renderFor: [
                { width: 750, height: 1334, deviceScaleFactor: 2, hasTouch: true, isMobile: true },
                { width: 1920, height: 1080 },
                { width: 720, height: 1280, isLandscape: true }
            ]   
        },

        // Use custom callback, which will execute before screenshot
        {
            url: 'https://example.com',
            tag: 'lots of kittens',
            async afterPageLoaded (page) {
                await page.click('#clickable-element')
            }
        },
        
        // All options combined
        {
            url: 'https://example.com',
            tag: 'horde of kittens',
            renderFor: ['desktop'],
            async afterPageLoaded (page) {
                await page.click('#clickable-element')
            }
        }
    ]
}