スプレッドシート の表形式のデータをmarkdwonに変換するTampermonkey のUserScript

Convert-spreadsheet-value-to-markdown-table.bookmarklet.js

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Convert-spreadsheet-value-to-markdown-table.user.js

// ==UserScript==
// @name         Convert spreadsheet value to markdown table
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  スプレッドシートの表形式のデータをmarkdown のtable フォーマットに変換するTampermonkeyスクリプト
// @author       K.Sakurai
// @resource     CSS1 https://cdn.jsdelivr.net/npm/toastify-js/src/toastify.min.css
// @require      https://cdn.jsdelivr.net/npm/toastify-js
// @match        http*://*/*
// @run-at       context-menu
// @grant        GM_addStyle
// @grant        GM_getResourceText
// @grant        GM_setClipboard
// ==/UserScript==
(function() {
    'use strict';
    // CSS読み込み
    GM_addStyle(GM_getResourceText('CSS1'));
    var value = window.prompt("SpreadSheet の値を markdownのtableに変換");
    if (value == null || value == "") {
        return;
    }
    var result = convertSheetValueToMarkdownTable(value);
    copyToClipBoardFrom(result);
    noticeMessage("texttile形式に変換しました");

    // クリップボードにコピーする
    function copyToClipBoardFrom(text) {
        GM_setClipboard(text);
    }
    
    // メッセージ通知
    function noticeMessage(text) {
        Toastify({
            text: text,
            duration: 3000,
            gravity: "bottom", // `top` or `bottom`
            position: 'right', // `left`, `center` or `right`
        }).showToast();
    }

    function convertSheetValueToMarkdownTable(str) {
        var rows = str.split((/[\n\u0085\u2028\u2029]|\r\n?/g)).map(function(row) {
            console.log(row)
            return row.split("\t")
        })
        var columnWidths = rows[0].map(function(column, columnIndex) {
            return columnWidth(rows, columnIndex)
        })
        console.log(columnWidths);
        var markdownRows = rows.map(function(row, rowIndex) {
            // | Name         | Title | Email Address  |
            // |--------------|-------|----------------|
            // | Jane Atler   | CEO   | jane@acme.com  |
            // | John Doherty | CTO   | john@acme.com  |
            // | Sally Smith  | CFO   | sally@acme.com |
            return "| " + row.map(function(column, index) {
                return column + Array(columnWidths[index] - column.length + 1).join(" ")
            }).join(" | ") + " |"
            row.map
        })
        markdownRows.splice(1, 0, "|" + columnWidths.map(function(width, index) {
            return Array(columnWidths[index] + 3).join("-")
        }).join("|") + "|")
        // https://www.w3.org/TR/clipboard-apis/#the-paste-action
        // When pasting, the drag data store mode flag is read-only, hence calling
        // setData() from a paste event handler will not modify the data that is
        // inserted, and not modify the data on the clipboard.
        return markdownRows.join("\n")
    }
    function columnWidth(rows, columnIndex) {
        return Math.max.apply(null, rows.map(function(row) {
            return row[columnIndex].length
        }))
    }
})();

補足

https://github.com/jonmagic/copy-excel-paste-markdown
上記を参考に作成。
右クリックで、プロンプトが立ち上がるので、スプレッドシート のタブ区切りデータを貼り付けると、
クリップボードにmarkdwon形式のデータがコピーできる。