Converts a basic HTML table into a CSV

html_table_to_csv.js

(function() {
    
    const result = []
    const tables = [...document.querySelectorAll('table')]
    
    const quoteRow = cols => ('"' + cols
        .map(it => it.textContent || '')
        .join('","') + '"')
    
    for (let i = 0, m = tables.length; i < m; i++) {
        
        const table = tables[i]
        const headers = [...table.querySelectorAll('th')]
        const rows = [...table.querySelectorAll('tr')]
        
        if (headers.length)
            result.push(quoteRow(headers))
        
        if (!rows?.length) continue
        
        for (let j = 0, n = rows.length; j < n; j++) {
            
            const row = rows[j]
            const cols = [...row.querySelectorAll('td')]
            
            if (!cols?.length) continue
            
            result.push(quoteRow(cols))
            
        }
        
    }
    
    console.log(result.join('\n'))
    
})()