javascript - regex - add space before any character that is not a letter -

i have tried many things , looking space added after character not letter. can replace non letter characters space, want space before character matched. @ moment have:

var str = 'div#some_id.some_class'; str = str.replace(/[^a-za-z0-9]/g, ' '); 

this provides me following,

div some_id some_class 

however looking result div #some_id .some_class

any appreciated.

you can try :

str = str.replace(/([^a-za-z0-9_])/g, ' $1') //omit 0-9 if you want space before them  //output: div #some_id .some_class