javascript - regexp to allow only one space in between words

Question

I'm trying to write a regular expression to remove white spaces from just the beginning of the word, not after, and only a single space after the word.

Used RegExp:

var re = new RegExp(/^([a-zA-Z0-9]+s?)*$/);

Test Exapmle:

1) test[space]ing - Should be allowed 
2) testing - Should be allowed 
3) [space]testing - Should not be allowed 
4) testing[space] - Should be allowed but have to trim it 
5) testing[space][space] - should be allowed but have to trim it 

Only one space should be allowed. Is it possible?

Answer 1

To match, what you need, you can use

var re = /^([a-zA-Z0-9]+s)*[a-zA-Z0-9]+$/;

Maybe you could shorten that a bit, but it matches _ as well

var re = /^(w+s)*w+$/;