const maxColumnWidth = (rows, columnIndex) => Math.max(...rows.map(row => row[columnIndex].length));
export default class PasteMarkdownTable {
constructor(clipboardData) {
this.data = clipboardData;
this.columnWidths = [];
this.rows = [];
this.tableFound = this.parseTable();
}
isTable() {
return this.tableFound;
}
convertToTableMarkdown() {
this.calculateColumnWidths();
const markdownRows = this.rows.map(
row =>
// | Name | Title | Email Address |
// |--------------|-------|----------------|
// | Jane Atler | CEO | jane@acme.com |
// | John Doherty | CTO | john@acme.com |
// | Sally Smith | CFO | sally@acme.com |
`| ${row.map((column, index) => this.formatColumn(column, index)).join(' | ')} |`,
);
// Insert a header break (e.g. -----) to the second row
markdownRows.splice(1, 0, this.generateHeaderBreak());
return markdownRows.join('\n');
}
// Private methods below
// To determine whether the cut data is a table, the following criteria
// must be satisfied with the clipboard data:
//
// 1. MIME types "text/plain" and "text/html" exist
// 2. The "text/html" data must have a single
element
// 3. The number of rows in the "text/plain" data matches that of the "text/html" data
// 4. The max number of columns in "text/plain" matches that of the "text/html" data
parseTable() {
if (!this.data.types.includes('text/html') || !this.data.types.includes('text/plain')) {
return false;
}
const htmlData = this.data.getData('text/html');
this.doc = new DOMParser().parseFromString(htmlData, 'text/html');
// Avoid formatting lines that were copied from a diff
const tables = this.doc.querySelectorAll('table:not(.diff-wrap-lines)');
// We're only looking for exactly one table. If there happens to be
// multiple tables, it's possible an application copied data into
// the clipboard that is not related to a simple table. It may also be
// complicated converting multiple tables into Markdown.
if (tables.length !== 1) {
return false;
}
const text = this.data.getData('text/plain').trim();
const splitRows = text.split(/[\n\u0085\u2028\u2029]|\r\n?/g);
// Now check that the number of rows matches between HTML and text
if (this.doc.querySelectorAll('tr').length !== splitRows.length) {
return false;
}
this.rows = splitRows.map(row => row.split('\t'));
this.normalizeRows();
// Check that the max number of columns in the HTML matches the number of
// columns in the text. GitHub, for example, copies a line number and the
// line itself into the HTML data.
if (!this.columnCountsMatch()) {
return false;
}
return true;
}
// Ensure each row has the same number of columns
normalizeRows() {
const rowLengths = this.rows.map(row => row.length);
const maxLength = Math.max(...rowLengths);
this.rows.forEach(row => {
while (row.length < maxLength) {
row.push('');
}
});
}
calculateColumnWidths() {
this.columnWidths = this.rows[0].map((_column, columnIndex) =>
maxColumnWidth(this.rows, columnIndex),
);
}
columnCountsMatch() {
const textColumnCount = this.rows[0].length;
let htmlColumnCount = 0;
this.doc.querySelectorAll('table tr').forEach(row => {
htmlColumnCount = Math.max(row.cells.length, htmlColumnCount);
});
return textColumnCount === htmlColumnCount;
}
formatColumn(column, index) {
const spaces = Array(this.columnWidths[index] - column.length + 1).join(' ');
return column + spaces;
}
generateHeaderBreak() {
// Add 3 dashes to line things up: there is additional spacing for the pipe characters
const dashes = this.columnWidths.map((width, index) =>
Array(this.columnWidths[index] + 3).join('-'),
);
return `|${dashes.join('|')}|`;
}
}