千分位分割

[coffeexy]

先记下别人写的正则：

let milliFormat = (num) => {  
    return num && num.toString()
        .replace(/^\d+/g, m => m.replace(/(?=(?!^)(\d{3})+$)/g, ','))
}

第一感觉是倒叙匹配

let milliFormat = (num) => {  
    return num && num.toString()
        .replace(/^\d+/g, m => {
          var array = [];
          for (i = m.length; i>3; ) {
            array.unshift(m.substr(i-3, 3));
            i = i - 3;
          }
          array.unshift(m.substring(0, i));
          return array.join(',');
        })
}

问陈日天，人说除1000啊

let milliFormat = (num) => {  
    return num && num.toString()
        .replace(/^\d+/g, m => {
          function me(v) {
            if (v<999) return v;
            return me(~~(v/1000)) + ',' + v%1000
          };
          return me(m);
        })
}