@telerik/kendo-intl/dist/es/numbers/group-integer.js

A package exporting functions for date and number parsing and formatting

export default function groupInteger(number, start, end, options, info) {
    var symbols = info.numbers.symbols;
    var decimalIndex = number.indexOf(symbols.decimal);
    var groupSizes = options.groupSize.slice();
    var groupSize = groupSizes.shift();

    var integerEnd = decimalIndex !== -1 ? decimalIndex : end + 1;

    var integer = number.substring(start, integerEnd);
    var result = number;
    var integerLength = integer.length;

    if (integerLength >= groupSize) {
        var idx = integerLength;
        var parts = [];

        while (idx > -1) {
            var value = integer.substring(idx - groupSize, idx);
            if (value) {
                parts.push(value);
            }
            idx -= groupSize;
            var newGroupSize = groupSizes.shift();
            groupSize = newGroupSize !== undefined ? newGroupSize : groupSize;

            if (groupSize === 0) {
                value = integer.substring(0, idx);
                if (value) {
                    parts.push(value);
                }
                break;
            }
        }

        integer = parts.reverse().join(symbols.group);
        result = number.substring(0, start) + integer + number.substring(integerEnd);
    }

    return result;
}