regex - Javascript replace all characters that are not a-z OR apostrophe -

i have around interwebs have yet find solid answer. seems pretty straight forward. let want replace characters in string not a-z , not , apostrophe. example:

with string "jeni's splendid ice cream" replace characters not a-z or apostrophe. have tried far is:

var term = "jeni's splendid ice cream" term.tolowercase().replace(/[^a-z]|[^\']/g, ''); 

but didn't seem work.... correct everyone? need sanity check, lol

or statements (|) belong inside group, in case unnecessary. regex should trick:

/[^a-z']/g 

working example:

var term = "jeni's splendid ice cream"  alert(term.tolowercase().replace(/[^a-z']/g, ''));