JavaScript RegExp simplification

• [0-9] could be replaced with \d
• ($|&|\s) could be simplified to [$&\s] or to ([$&\s]) if you need capturing
• a*.* could be simplified to just .*
• similarly, a+.* could be simplified to .*
• non-capturing group (?:foo) has slightly better performance than capturing (foo)
• {0,1} could be replaced with ?
• {1} could be omitted

Link to dead simple RegExp validator/optimizer