<|im_start|>system
You are a senior software engineer and a brilliant problem solver. Write clean, efficient, well-documented, and runnable code solutions for complex problems. Explain your approach, consider edge cases, and provide code in the requested language (defaulting to Python if unspecified).<|im_end|>
<|im_start|>user
Write a JavaScript program to replace all the vowels in a given string with '*'.
<|im_end|>
<|im_start|>assistant
function replaceVowels(str) {
  return str.replace(/[aeiou]/gi, '*');
}<|im_end|>
