Valid commands for evaluate button:

number of <chunk> in [ <chunk> <number> [ to <number>] [ of ... ] of ] "<string>"
start of [ <chunk> <number> [ to <number>] [ of ... ] of ] "<string>"
end of [ <chunk> <number> [ to <number>] [ of ... ] of ] "<string>"
get [ <chunk> <number> [ to <number>] [ of ... ] of ] "<string>"
delete [ <chunk> <number> [ to <number>] [ of ... ] of ] "<string>"
put "<string>" into [ <chunk> <number> [ to <number>] [ of ... ] of ] "<string>"
put "<string>" before [ <chunk> <number> [ to <number>] [ of ... ] of ] "<string>"
put "<string>" after [ <chunk> <number> [ to <number>] [ of ... ] of ] "<string>"

Download the library: chunkex.js

Instructions for use:

cxl_count(text, tokens);
    text is, for example, "Apple Computer, Inc."
    tokens is an array, for example, ('chars', 'word', 2)
    result in this case would be 9 (number of CHARS in WORD 2 of ...)

cxl_get(text, tokens);
    text is, for example, "Apple Computer, Inc."
    tokens is an array, for example, ('char', 3, 4, 'word', 2, 3)
    result in this case would be "mp" (get CHAR 3 to 4 of WORD 2 to 3 of ...)

cxl_delete(text, tokens);
    text is, for example, "Apple Computer, Inc."
    tokens is an array, for example, ('char', 6, 8, 'word', 2)
    result in this case would be "Apple Compu, Inc." (delete CHAR 6 to 8 of WORD 2 of ...)

Get the idea?

cxl_start(text, tokens) returns the position of the first
    character of the chunk expression, starting from zero.

cxl_end(text, tokens) returns the position of the last
    character of the chunk expression, starting from zero, plus one.

(These two are used with JavaScript's substring() method on strings.)

cxl_into(text, tokens, newtext) inserts newtext
    into (tokens) of text.

cxl_before(text, tokens, newtext) inserts newtext
    before (tokens) of text.

cxl_after(text, tokens, newtext) inserts newtext
    after (tokens) of text.

NOTICE!

This:

text = cxl_delete(text, tokens);

DOES NOT do the same thing as this:

var s = cxl_start(text, tokens);
var e = cxl_end(text, tokens);
text = text.substring(0,s) + text.substring(e,text.length);

E.g., with text == "Apple Computer, Inc." and tokens == ('word', 2), the first method (cxl_delete) gives "Apple Inc.", and second method (substring) gives "Apple  Inc.". Notice the extra space.