node_modules/cli-progress/lib/formatter.js

const _stringWidth = require('string-width');
const _defaultFormatValue = require('./format-value');
const _defaultFormatBar = require('./format-bar');
const _defaultFormatTime = require('./format-time');

// generic formatter
module.exports = function defaultFormatter(options, params, payload){

    // copy format string
    let s = options.format;

    // custom time format set ?
    const formatTime = options.formatTime || _defaultFormatTime;
    
    // custom value format set ?
    const formatValue = options.formatValue || _defaultFormatValue;

    // custom bar format set ?
    const formatBar = options.formatBar || _defaultFormatBar;

    // calculate progress in percent
    const percentage =  Math.floor(params.progress*100) + '';

    // bar stopped and stopTime set ?
    const stopTime = params.stopTime || Date.now();

    // calculate elapsed time
    const elapsedTime = Math.round((stopTime - params.startTime)/1000);

    // merges data from payload and calculated
    const context = Object.assign({}, payload, {
        bar:                    formatBar(params.progress, options),

        percentage:             formatValue(percentage, options, 'percentage'),
        total:                  formatValue(params.total, options, 'total'),
        value:                  formatValue(params.value, options, 'value'),

        eta:                    formatValue(params.eta, options, 'eta'),
        eta_formatted:          formatTime(params.eta, options, 5),
        
        duration:               formatValue(elapsedTime, options, 'duration'),
        duration_formatted:     formatTime(elapsedTime, options, 1)
    });

    // assign placeholder tokens
    s = s.replace(/\{(\w+)\}/g, function(match, key){
        // key exists within payload/context
        if (typeof context[key] !== 'undefined') {
            return context[key];
        }

        // no changes to unknown values
        return match;
    });

    // calculate available whitespace (2 characters margin of error)
    const fullMargin = Math.max(0, params.maxWidth - _stringWidth(s) -2);
    const halfMargin = Math.floor(fullMargin / 2);

    // distribute available whitespace according to position
    switch (options.align) {

        // fill start-of-line with whitespaces
        case 'right':
            s = (fullMargin > 0) ? ' '.repeat(fullMargin) + s : s;
            break;

        // distribute whitespaces to left+right
        case 'center':
            s = (halfMargin > 0) ? ' '.repeat(halfMargin) + s : s;
            break;

        // default: left align, no additional whitespaces
        case 'left':
        default:
            break;
    }

    return s;
}