Reorder Log Files

let reorderLogFiles = function(logs) {

    let alpha = [],
        numbers = [];

    const isNumber = (str) => {
        const [, content] = str.split(' ');
        return content.match(/\d+/);
    }

    const getBody = (str) => {
        return str.substring(str.indexOf(' ') + 1);
    }

    // separate alpha from numbers
    logs.forEach(log => {
        if (isNumber(log)) {
            numbers.push(log);
        }
        else {
            alpha.push(log);
        }
    });

    let comparator = (x, y) => {
        let compareResult = getBody(x).localeCompare(getBody(y));
        if (compareResult === 0) {
           return x.localeCompare(y);
        }
        return compareResult;
    }

    return [...alpha.sort(comparator), ...numbers];
};