boy, man,girl, woman,tyrannosaurus rex, lion

hat, cat, rat, c3po, @gmail

/^w(s*,?s*w)*$/

/^s*w(s*,?s*w)*s*$/

/^s*[a-z0-9](s*,?s*[a-z0-9])*s*$/

/^s*([a-z0-9]+(s[a-z0-9]+)*)(s*,s*([a-z0-9]+(s[a-z0-9]+)*))*s*$/

var re = /^(w+,? ?)+$/;
var str1 = "boy, man,girl, woman,tyrannosaurus rex, lion";
var str2 = "hat, cat, rat, c3po, @gmail";
alert(str1.test(re));  // true
alert(str2.test(re));  // false

/^(w+s?[ws]*)(,s*w+s?[ws]*)*$/

Assert position at the beginning of a line (at beginning of the string or after a line break character) «^»
Match the regular expression below and capture its match into backreference number 1 «(w+s?[ws]*)»
   Match a single character that is a “word character” (letters, digits, and underscores) «w+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
   Match a single character that is a “whitespace character” (spaces, tabs, and line breaks) «s?»
      Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
   Match a single character present in the list below «[ws]*»
      Between zero and unlimited times, as many times as possible, giving back as needed (greedy) «*»
      A word character (letters, digits, and underscores) «w»
      A whitespace character (spaces, tabs, and line breaks) «s»
Match the regular expression below and capture its match into backreference number 2 «(,s*w+s?[ws]*)*»
   Between zero and unlimited times, as many times as possible, giving back as needed (greedy) «*»
   Note: You repeated the capturing group itself.
   The group will capture only the last iteration.
   Put a capturing group around the repeated group to capture all iterations. «*»
   Match the character “,” literally «,»
   Match a single character that is a “whitespace character” (spaces, tabs, and line breaks) «s*»
      Between zero and unlimited times, as many times as possible, giving back as needed (greedy) «*»
   Match a single character that is a “word character” (letters, digits, and underscores) «w+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
   Match a single character that is a “whitespace character” (spaces, tabs, and line breaks) «s?»
      Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
   Match a single character present in the list below «[ws]*»
      Between zero and unlimited times, as many times as possible, giving back as needed (greedy) «*»
      A word character (letters, digits, and underscores) «w»
      A whitespace character (spaces, tabs, and line breaks) «s»
Assert position at the end of a line (at the end of the string or before a line break character) «$»


Created with RegexBuddy

/^s*[a-z0-9]+(s+[a-z0-9]+)?(s*,s*[a-z0-9]+(s+[a-z0-9]+)?)*s*$/