html-tables-to-json/build/src/parser.js

Parser for HTML to JSON

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.CheerioTableParser = void 0;
const cheerio = require("cheerio");
// TODO: TableParser should be an interface
/**
 * Parses HTML into a DOM tree using Cheerio.
 */
class CheerioTableParser {
    /**
     * @returns array of cheerio instances representing the tables in the document
     */
    parse(doc) {
        this.$ = cheerio.load(doc);
        const result = [];
        const $tables = this.$("table");
        if ($tables.length === 0) {
            throw new Error("No tables found");
        }
        $tables.each((_, table) => {
            result.push(this.expandColspanRowspan(this.parseTr(this.$(table))));
        });
        return result;
    }
    /**
     * Given a list of <tr>s, return a list of text rows.
     *
     * @see Any cell with `rowspan` or `colspan` will have its contents copied
     *      to subsequent cells.
     * @param $rows list of cheerio instances representing rows
     * @returns array of array, each returned row is a list of string text.
     */
    expandColspanRowspan($rows) {
        const allTexts = [];
        let remainder = []; // [index, text, rowspan]
        $rows.each((_, tr) => {
            const texts = [];
            const nextRemainder = [];
            let index = 0;
            const $tds = this.parseTd(this.$(tr));
            $tds.each((_, td) => {
                // push texts from previous rows with rowspan > 1 that come
                // before this <td>
                while (remainder.length > 0 &&
                    remainder[0] &&
                    remainder[0][0] <= index) {
                    const [prevIndex, prevText, prevRowspan] = remainder[0];
                    texts.push(prevText);
                    if (prevRowspan > 1) {
                        nextRemainder.push([prevIndex, prevText, prevRowspan - 1]);
                    }
                    index++;
                    remainder.shift();
                }
                const $td = this.$(td);
                // push the text from this <td>, colspan times
                const text = $td.text().trim();
                const rowspan = parseInt($td.attr("rowspan") || "1", 10);
                const colspan = parseInt($td.attr("colspan") || "1", 10);
                for (let i = 0; i < colspan; i++) {
                    texts.push(text);
                    if (rowspan > 1) {
                        nextRemainder.push([index, text, rowspan - 1]);
                    }
                    index++;
                }
            });
            for (const [prevIndex, prevText, prevRowspan] of remainder) {
                texts.push(prevText);
                if (prevRowspan > 1) {
                    nextRemainder.push([prevIndex, prevText, prevRowspan - 1]);
                }
            }
            allTexts.push(texts);
            remainder = nextRemainder;
        });
        return allTexts;
    }
    /**
     * Return the list of row elements from the parsed table element.
     *
     * @param $table the table to parse
     * @returns array of cheerio instances representing the rows in the table
     */
    parseTr($table) {
        return $table.find("tr");
    }
    /**
     * @param $row the row to parse
     * @returns array of cheerio instances representing the cells in the row
     */
    parseTd($row) {
        return $row.find("td, th");
    }
}
exports.CheerioTableParser = CheerioTableParser;
//# sourceMappingURL=parser.js.map