Hey Tony, Yeah that’s what I eventually realized so I changed what happens when I reach zero. I was just wanting to understand the inner workings better.
On Mon, Jun 28, 2021 at 7:34 AM TW Tones <[email protected]> wrote: > Another way to look at it ; > Butlast purpose discard the last N input title(s) > > So saying "discard the last 0 input titles" is non sensical > If you actually want to discard 3, then 2 then 1 perhaps you filter needs > find another way once it reaches 0 > > Tones > On Monday, 28 June 2021 at 13:07:37 UTC+10 History Buff wrote: > >> Thanks Eric, >> >> I appreciate that. I looked at it, but I really don’t know JavaScript. >> Makes me want to learn though. >> >> >> >> On Sun, Jun 27, 2021 at 12:07 PM Eric Shulman <[email protected]> wrote: >> >>> On Sunday, June 27, 2021 at 11:28:50 AM UTC-7 History Buff wrote: >>> >>>> I don't understand why a 0 in the butlast operator would yield no >>>> results >>>> >>> >>> The butlast[] operator is defined in this shadow tiddler: >>> https://tiddlywiki.com/#%24%3A%2Fcore%2Fmodules%2Ffilters%2Flistops.js >>> >>> Here's the javascript code from that tiddler: >>> exports.butlast = function(source,operator,options) { >>> var count = $tw.utils.getInt(operator.operand,1), >>> results = []; >>> source(function(tiddler,title) { >>> results.push(title); >>> }); >>> return results.slice(0,-count); >>> }; >>> >>> The first line gets the operand value, defaulting to 1. >>> The next 4 lines copy the entire list of items into a results array >>> The last line uses the javascript slice() function to remove items from >>> the results array and then return that array >>> >>> Here's the documentation for the javascript slice() function: >>> >>> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice >>> >>> Note the description of the "end" parameter: >>> Zero-based index before which to end extraction. slice extracts up to *but >>> not including* end. >>> >>> Thus, when you used butlast[0], the filter code invokes slice(0,-0), >>> i.e., "*starting from the first item up to but not including the first >>> item*" >>> which results in *no items* being returned. >>> >>> enjoy, >>> -e >>> >> -- >>> You received this message because you are subscribed to a topic in the >>> Google Groups "TiddlyWiki" group. >>> To unsubscribe from this topic, visit >>> https://groups.google.com/d/topic/tiddlywiki/lROJc--2xFI/unsubscribe. >>> To unsubscribe from this group and all its topics, send an email to >>> [email protected]. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/tiddlywiki/c1f40a73-746d-4c39-89b9-6786c9caee0fn%40googlegroups.com >>> <https://groups.google.com/d/msgid/tiddlywiki/c1f40a73-746d-4c39-89b9-6786c9caee0fn%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- > You received this message because you are subscribed to a topic in the > Google Groups "TiddlyWiki" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/tiddlywiki/lROJc--2xFI/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/tiddlywiki/faaa280d-a866-47d3-abef-5ec8e51e5d5dn%40googlegroups.com > <https://groups.google.com/d/msgid/tiddlywiki/faaa280d-a866-47d3-abef-5ec8e51e5d5dn%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "TiddlyWiki" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/tiddlywiki/CAD1WRcbRkWRSjCp3Wi6Zjpq_q8Y8ZoVGU%2BoQ9DW%3D_9Fa%2Bjq%3D4w%40mail.gmail.com.
