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@remotemerge/hali

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@remotemerge/hali

Hali is an open source, lightweight and modern JavaScript utility to evaluate XPath expressions built on top of TypeScript.

2.0.5
latest
Source
npm

Version published: 2 years ago

Weekly downloads: 0

Maintainers: 1

Weekly downloads

Created: 5 years ago

Source

Hali

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Hali is an open source, lightweight and modern JavaScript utility to evaluate XPath expressions built on top of TypeScript. This tool is built for web scraping and can be integrated into new or existing web crawlers.

Install

# using NPM
npm i @remotemerge/hali
# using Yarn
yarn add @remotemerge/hali

Usage

Hali source file is index.ts.

Use index.ts in TypeScript environment.

import Hali from '@remotemerge/hali'

Use dist/index.js in NodeJS or ES5/ES6..ESNext environment.

import Hali from '@remotemerge/hali/dist/index.js'
// or bit older
const Hali = require('@remotemerge/hali/dist/index.js')

Examples

The Hali constructor Hali(html|DOM) supports both DOM and HTML string, initialize as required.

const myHali = new Hali('<html>...</html>');

Scrape First Match

This method evaluates the given expression and captures the first result. It is useful for scraping a single element value like title, price, etc from HTML pages.

const result = myHali.queryFirst('//span[@id="productTitle"]');
console.log(result);

Sample output:

LETSCOM Fitness Tracker HR, Activity Tracker Watch with Heart Rate...

Scrape All Matches

This method evaluates the given expression and captures all results. It is useful for scraping all URLs, all images, all CSS classes, etc from HTML pages.

// scrape titles
const results = myHali.queryList('//span[contains(@class, "zg-item")]/a/div');
console.log(results);

Sample output:

['Cell Phone Stand,Angle Height Adjusta…', 'Selfie Ring Light with Tripod…', 'HOVAMP MFi Certified Nylon…', '...']

Scrape multiple elements

This method loop through the given expressions and captures the first match of each expression. It is useful for scraping full product information (title, seller, price, rating, etc.) from HTML pages. The keys are preserved and the values are returned to the same keys.

const result = myHali.multiQuery({
  title: '//div[@id="ppd"]//span[@id="productTitle"]',
  seller: '//div[@id="ppd"]//a[@id="bylineInfo"]',
  price: '//div[@id="ppd"]//span[@id="priceblock_dealprice"]',
  rating: '//div[@id="ppd"]//span[@id="acrCustomerReviewText"]',
});

Sample output:

{
    title: 'LETSCOM Fitness Tracker HR, Activity Tracker Watch with Heart Rate Monitor...',
    seller: 'LETSCOM',
    price: '$20.39',
    rating: '1,489 ratings',
}

Scrape with SubQueries

This method captures the root element and runs queries within its namespace. It is useful for scraping multiple products and full information about each product. For example, there can be 10 products on a page and each product has (title, url, image, price, etc.). This method also supports pagination parameter. The keys are preserved and the values are returned to the same keys. Here pagination is optional parameter.

const result = myHali.subQuery({
  root: '//span[contains(@class, "zg-item")]',
  pagination: '//ul/li/a[contains(text(), "Next")]/@href',
  queries: {
    title: 'a/div/@title',
    url: 'a/@href',
    image: 'a/span/div/img/@src',
    price: './/span[contains(@class, "a-color-price")]',
  }
});
console.log(result);

Sample output:

{
  paginationUrl: 'https://www.example.com/gp/new-releases/wireless/reTF8&pg=2',
  results: [
    {
      title: 'Cell Phone Stand,Angle Height Adjustable Stab/Kindle/Tablet,4-10inch',
      url: '/Adjustable-LISEN-Aluminum-Compatible-4-10&refRID=H1HWDWERK8YCRN76ER1T',
      image: 'https://images-na.ssl-images-example.com/images/I/61UL200_SR200,200_.jpg',
      price: '$16.99'
    },
    {
      title: 'Selfie Ring Light with Tripod Stand and Pheaming Photo Photography Vlogging Video',
      url: '/Selfie-Lighting-Steaming-Photography-Vlogging/dp/B081SV&K8YCRN76ER1T',
      image: 'https://images-na.ssl-images-example.com/images/I/717L200_SR200,200_.jpg',
      price: '$46.99'
    },
    {
      // ...
    }
  ]
}

Wait for Element

This method waits until the element (matches by expression) exists on a page. The first parameter expression is XPath expression to match and the second parameter maxSeconds is the maximum time to wait in seconds (default to 10 seconds).

myHali.waitXPath('//span[contains(@class, "a-color-price")]/span')
  .then((response) => {
    // expression match and element exists
  }).catch((error) => {
  // match nothing and timeout
});

Contribution

Welcome the community for contribution. Please make a PR request for bug fixes, enhancements, new features, etc.

Disclaimer

All the XPath expressions above are tested on Amazon product listing and related pages for educational purposes only. The icons are included from flaticon website.

Keywords

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Package last updated on 17 Jul 2022

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