What is the meaning of /i at the tail of this regex?
/i
var time = /^([1-9]|1[0-9]):([0-5][0-9])(\\s[a|p]m)$/i;
/i stands for ignore case in the given string. Usually referred to as case-insensitive as pointed out in the comment.
It's, like Sachin Shanbhag already answered the 'ignore case' modifier. So /[a-z]/i is equal to /[a-zA-Z]/. Check this link for other modifiers.
/[a-z]/i
/[a-zA-Z]/