正则表达式以匹配更多可能性（javascript）

Question

This regex (for base64):

/[a-zA-Z0-9/+]{5}/g

Would match every 5 characters in a string. So if I have:

"19jZ2uLj5OXm5+jp6vLz9PX29/j5+v/aAAw"

the matches are:

1. 19jZ2
2. uLj5O
3. Xm5+j
4. p6vLz
5. 9PX29
6. /j5+v
7. /aAAw

How would I write a regex that would result in the following matches?

1. 19jZ2
2. 9jZ2u
3. jZ2uL
4. Z2uLj
5. 2uLj5
6. uLj5O
7. and so on...

(^Literally every possible 5 consecutive characters in the string)

Answer 1

How about this:

"19jZ2uLj5OXm5+jp6vLz9PX29/j5+v/aAAw".split('').map(function(elm, i, arr) { 
    return arr.slice(i,i+5).join('') }
).slice(0,-4)

Answer 2

Based on adeneo's comment :

var result = [],
    s = '19jZ2uLj5OXm5+jp6vLz9PX29/j5+v/aAAw';
while (s.length > 4) {
    result.push(s.substr(0, 5));
    s = s.substr(1);
}

Answer 3

Here is a suggestion :

function split(s) {
    var allowed = /^[a-z\d/+]{5}/i,
        result = [],
        match;
    while (s.length > 4) {
        match = s.match(allowed);
        match && result.push(match[0]);
        s = s.substr(1); // removes first char
    }
    return result;
}

The regex looks for the first five chars for each loop :

split('19jZ2uLj5OXm5+jp6vLz9PX29/j5+v/aAAw'); // ['19jZ2', '9jZ2u', ...]
split('19jZ2=uLj5OXm5+jp6vLz9PX29/j5+v/aAAw'); // ['19jZ2', 'uLj5O', ...]

Answer 4

A simple ([a-zA-Z0-9+\\/]{5}) could do it for this specific input

Live DEMO

Or (?:"|\\G(?<!^))([a-zA-Z0-9+\\/]{5}|[a-zA-Z0-9+\\/]+)(?=.*?") if your string is between quotes

Live DEMO

Or (?:"|\\G(?<!^))([a-zA-Z0-9+\\/]{5})(?=(?:[a-zA-Z0-9+\\/]{5})*") if your string count is exactly a multiple of 5

Live DEMO