str = str.replace（/ / g ，'，'）; 
 

以下是一个更好的方法，它将替换所有的空白字符串：

  str = str.replace（/ \s + / g，'，'）; 
 

im new with regexp, so can i ask for some assistance

Using string.replace function what code that can replace spaces with comma

Input:The quick brown fox jumps over the lazy dog. Output:The,quick,brown,fox,jumps,over,the,lazy dog.

Thanks

Like this:

str = str.replace(/ /g, ',');

Here's a better one which will replace all strings of whitespace:

str = str.replace(/\s+/g, ',');