怎么去掉正则外面的字符串

Question

比如：var reg = "/1\d{10}/"
怎么去掉外面的字符串，使:
var reg = /1\d{10}/

Answer 1

var reg = "/1\d{10}/"
reg = new RegExp(reg)    // /1\d{10}/

Answer 2

var reg = "/1\d{10}/";
reg = eval(reg);