alpha-sortable

Encode/decode numbers in strings so that they sort properly

Why?

• Because sometimes you want items sorted in numeric order, even though they are sorted on a text field. Example: filenames.
• Zero padding only works if your users are okay with lots of zeros, and/or you know your numbers will never get large.

How?

1. Zero-pad to a reasonable amount -- like how big you think things will probably get in the life of the system
2. When you get bigger numbers, prefix them with a flagged length that keeps them sorting properly. The flag is an 'E' for every digit in the length counter, followed by the length counter, followed by a hyphen.

A few examples (more below):

|Number|Encoded with default setting {length: 4}| |------|-------| |1|0001| |10|0010| |100|0100| |1000|1000| |10000|E5-10000| |100000000|E9-100000000|
|1000000000|EE10-1000000000| |1e+100|EEE101-10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000|

API

import {stringify, parse} from 'alpha-sortable'

console.log(stringify(20))
// => 0020

console.log(stringify(20, {length: 2}))
// => 20

console.log(stringify(20000000))
// => E8-20000000

console.log(parse('E8-20000000') === 20000000)
// true

More Examples

Here's the full output of demo-table.js : |Number|BigInt|encoded {length: 4}| |------|------|-------| |0|0n|0000| |1|1n|0001| |9|9n|0009| |10|10n|0010| |99|99n|0099| |100|100n|0100| |999|999n|0999| |1000|1000n|1000| |9999|9999n|9999| |10000|10000n|E5-10000| |99999|99999n|E5-99999| |100000|100000n|E6-100000| |999999|999999n|E6-999999| |1000000|1000000n|E7-1000000| |9999999|9999999n|E7-9999999| |10000000|10000000n|E8-10000000| |99999999|99999999n|E8-99999999| |100000000|100000000n|E9-100000000| |999999999|999999999n|E9-999999999| |1000000000|1000000000n|EE10-1000000000| |9999999999|9999999999n|EE10-9999999999| |10000000000|10000000000n|EE11-10000000000| |99999999999|99999999999n|EE11-99999999999| |100000000000|100000000000n|EE12-100000000000| |999999999999|999999999999n|EE12-999999999999| |1000000000000|1000000000000n|EE13-1000000000000| |9999999999999|9999999999999n|EE13-9999999999999| |10000000000000|10000000000000n|EE14-10000000000000| |99999999999999|99999999999999n|EE14-99999999999999| |100000000000000|100000000000000n|EE15-100000000000000| |999999999999999|999999999999999n|EE15-999999999999999| |1000000000000000|1000000000000000n|EE16-1000000000000000| |10000000000000000|9999999999999999n|EE16-9999999999999999| |10000000000000000|10000000000000000n|EE17-10000000000000000| |100000000000000000|99999999999999999n|EE17-99999999999999999| |100000000000000000|100000000000000000n|EE18-100000000000000000| |1000000000000000000|999999999999999999n|EE18-999999999999999999| |1000000000000000000|1000000000000000000n|EE19-1000000000000000000| |10000000000000000000|9999999999999999999n|EE19-9999999999999999999| |10000000000000000000|10000000000000000000n|EE20-10000000000000000000| |100000000000000000000|99999999999999999999n|EE20-99999999999999999999| |100000000000000000000|100000000000000000000n|EE21-100000000000000000000| |1e+21|999999999999999999999n|EE21-999999999999999999999| |1e+21|1000000000000000000000n|EE22-1000000000000000000000| |1e+22|9999999999999999999999n|EE22-9999999999999999999999| |1e+22|10000000000000000000000n|EE23-10000000000000000000000| |1e+23|99999999999999999999999n|EE23-99999999999999999999999| |1e+23|100000000000000000000000n|EE24-100000000000000000000000| |1e+24|999999999999999999999999n|EE24-999999999999999999999999| |1e+24|1000000000000000000000000n|EE25-1000000000000000000000000| |1e+25|9999999999999999999999999n|EE25-9999999999999999999999999| |1e+25|10000000000000000000000000n|EE26-10000000000000000000000000|

FAQ

Q. Isn't there some standard way to do this?

A. Not that I could find.

Q. Is there a maximum number it can handle?

A. No. For example, it could handle a googolplex by starting with a googol 'E' characters. No problem! (Of course, no computer in this universe will ever be able to hold a number as large as a googolplex.)

Q. Why 'E'

A. It has to be a character that sorts after 9, which is most of them. Since the notation is very similar to scientific notation, 'E' seemed like a good idea. We also want it to be a character that's going to be legal in pretty much every context, including URLs. 'E' and hyphen seem to pass that test.

Q. Does the 'E' have to be uppercase?

A. Let's say yes. We don't have a clear example of where a lowercase E would break something, but it seems like a bad idea.