Question

I am faced with two problems. (with jQuery)

for (var i=0; i<len; i++) {
    var e = arr[i],               //<- strings
        re = new RegExp(e,"ig");
    target.html(
        target.html().replace(
            re, "<span class='rep'>" + e + "</span>"
        )
    );
}

1. The original value cannot be called after replacing. (like a “$1”)
2. It cannot replace, if the candidate for substitution (property e) has a single quote.

Answer 1

You actually can use something similar to $1:

for (var i=0; i<len; i++) {
    var e = arr[i],               //<- strings
        re = new RegExp(e,"ig");
    target.html(
        target.html().replace(
            re, "<span class='rep'>$&</span>"
        )
    ); //you could also have used $1 to refer to the first backreference, instead of the entire match
}

Your second problem is less clear to me. Single quotes are not special characters in regexes.

I could not replicate your other problem. Here is a working example: http://jsfiddle.net/Xsjt7/1/