javascript - jQuery alphabetical only with numeric -

i'm having difficulties jquery validation. need make input validation alphabetical numeric, shouldn't validate if put numeric value.

for example: lorem ipsum 123 should valid, lorem ipsum should valid, 123 shouldn't valid.

i use code doesn't work properly.

e.find('.alphanum').keypress(function(e) {     var regex = new regexp("^[a-za-z0-9 ]+$");     var str = string.fromcharcode(!e.charcode ? e.which : e.charcode);     if (regex.test(str)) {         return true;     }     e.preventdefault();     return false; }); 

this might useful:

/^(?:[a-za-z0-9 ]*[a-za-z ][0-9]*)+$/ 

it same thing 1 provided qwertiy, might simpler understand (which, imho, quality in when comes regular expressions...).

what happens form non-capturing group of 0 or more allowed characters, 1 required character, , 0 or more allowed not required characters, , match group. if don't want allow only-whitespace strings either, move space second third character class, i.e.

/^(?:[a-za-z0-9 ]*[a-za-z][0-9 ]*)+$/ 

you can think of 3 character classes as

1. all characters allowed in string.
2. all characters must occur @ least once
3. all characters appear in 1., not in 2.

it's possible more inefficient qwertiy's answer, solution matches e.g. " ", while second 1 in answer doesn't.

you can fiddle regex, , test results, here: https://regex101.com/r/ib6pe1/3