Table builder (Time limit 2h30)

table.js

function printTable(table) {
    const options = {
        padding: 1,
        columns: table.reduce(parseColumns, []),
        lineSize: 1,
    };

    options.lineSize = options.columns.reduce((num, col) => {
        return num + col.size + (options.padding * 2) + 1;
    }, 1);

    function parseColumns(cols, row) {
        for (let key in row) {
            const len = parseEntry(row[key]).length;
            let present = false;
            for (let i = 0; i < cols.length; i++) {
                if (cols[i].key === key) {
                    present = true;
                    if (cols[i].size < len) cols[i].size = len;
                    continue;
                }
            }
            if (!present) cols.push({ key, size: Math.max(len, key.length) });
        }
        return cols;
    }

    function line() {
        return '-'.repeat(options.lineSize);
    }

    function pre() {
        return ' '.repeat(options.padding);
    }

    function post(value, column) {
        return ' '.repeat(Math.max(0, column.size - value.length) + options.padding);
    }

    function header() {
        return `|${options.columns.map(col => cell(col.key, col)).join('|')}|`;
    }

    function parseEntry(value) {
        if (value === undefined) value = '';
        if (typeof value !== 'string') value = JSON.stringify(value);
        return value;
    }

    function cell(value, column) {
        return `${pre()}${value}${post(value, column)}`;
    }

    function row(cells, index) {
        return `|${options.columns.map((col) => {
            return cell(parseEntry(cells[col.key]), col);
        }).join('|')}|`;
    }

    return [
        line(), '\n',
        header(), '\n',
        line(), '\n',
        table.map(row).join('\n'), '\n',
        line(), '\n'
    ].join('');
}