javascript function which ensures a text contains only dollar symbols formatted as $placeholder$

I need a javascript function which gets a string and returns false if the string contains
- Any unclosed dollar symbol
- Or a closed dollar symbol with something between dollars different than a series of characters

function validateFormat(text) {
// Do stuff
}

For example if text:

validateFormat("blab abalaba $something$ avava $affo$")  -> true
validateFormat("blab abalaba $something$ avava $ affo$") -> false because of the white space
validateFormat("blab abalaba $1so3mething$ avava $affo$") -> false because of the numbers
validateFormat("blab abalaba $something") -> false because of unclosed placeholder

Can someone help me?

From stackoverflow

• // delete all valid placeholders
  text = text.replace(/\$[a-z]+\$/gi, "");
  
  // are there any "$" left?
  if (text.search(/\$/) != -1) {
      return false;
  }
  return true;
  

  This is another solution:

  matches = text.match(/\$[a-z]+\$|\$/gi);
  if (matches) {
      for (var i = 0; i < matches.length; i++) {
          if (matches[i] == '$') { return false };
      }
  }
  return true;
  

• Another way:

  text.match(/\$/g).length/2 == text.match(/\$[a-z]+\$/g).length
  

  This counts the number of $ and compares it to the number of $foobar$.

  Georg : Isn't there a .length missing?

  Georg : btw: I like this solution very much.

  Gumbo : Woops. Thanks for the remark, gs.