千分位格式化

const formater_number = (n: number | string) => {
    let nStr = n + '';    //数字转换为字符
    let x, x1, x2;
    if (nStr.indexOf('.') != -1) {
        x = nStr.split('.');    //按照小数点分割
        x1 = x[0];     //整数部分
        x2 = x.length > 1 ? '.' + x[1] : '';    //小数部分
    } else {
        x1 = nStr;
        x2 = '';
    }
    if (x1.indexOf(',') != -1) {
        //如果含有千分位
        let rgx1 = new RegExp(',', 'g');
        let newV = x1.replace(rgx1, '');
        const rgx = /(\d+)(\d{3})/;
        while (rgx.test(newV)) {
            //正则式匹配
            newV = newV.replace(rgx, '$1' + ',' + '$2');     //正则式替换
        }
        return newV + x2;
    } else {
        //不含千分位
        const rgx = /(\d+)(\d{3})/;      //正则式定义
        while (rgx.test(x1)) {
            x1 = x1.replace(rgx, '$1' + ',' + '$2')    //正则式替换
        }
        return x1 + x2;
    }
}