Set column width to "fit" data for SheetJS work sheet (https://www.npmjs.com/package/xlsx)

sheet-js-auto-column-width.js

const removeDuplicatesInArray = array => {
    return array.filter((elem, pos) => array.indexOf(elem) === pos);
};

const applyAutoWidth = (XLSXWorkSheet, widthMultiplier) => {
    widthMultiplier = widthMultiplier || 1.25;

    const cellsKeys = Object.keys(XLSXWorkSheet).filter(key => key.match(/^[A-Z]+\d+$/)),
        columns = removeDuplicatesInArray(cellsKeys.map(key => key.replace(/\d/g, '')));

    const getMaxLengthOfColumn = column => {
        const regExp = new RegExp('^' + column + '\\d+$'),
            keysOfColumn = cellsKeys.filter(key => key.match(regExp));

        return keysOfColumn.reduce((max, key) => {
            const cellLength = (XLSXWorkSheet[key].v + '').length;
            return cellLength > max ? cellLength : max;
        }, 0);
    };

    if (XLSXWorkSheet['!cols'] == null) {
        XLSXWorkSheet['!cols'] = [];
    }

    columns.forEach((column, index) => {
        if (XLSXWorkSheet['!cols'][index] == null) {
            XLSXWorkSheet['!cols'][index] = {};
        }

        Object.assign(XLSXWorkSheet['!cols'][index], {width: getMaxLengthOfColumn(column) * widthMultiplier});
    });
};