var reg1 = /(\w)\1\1/g; //判断2个连续字符
var reg2 = /(\w)\1{2}/g; //判断3个连续字符
var reg3 = /(\w)\1\1/g;  //判断3个连续字符
 
var str = 'aa!@#123AaAaAAA3';
 
str.match(reg1); // 输出['aa','AA']
str.match(reg2); // 输出['AAA']
str.match(reg3); // 输出['AAA']

//reg2和reg3表达的意思相同