mystring.replace(new RegExp('.', "g"), ' ');

还有一个很容易理解的解决方案:)

var newstring = mystring.split('.').join(' ');

这更简洁/可读，应该比Fagner Brack发布的更好(toLowerCase不是在循环中执行的):

String.prototype.replaceAll = function(search, replace, ignoreCase) {
  if (ignoreCase) {
    var result = [];
    var _string = this.toLowerCase();
    var _search = search.toLowerCase();
    var start = 0, match, length = _search.length;
    while ((match = _string.indexOf(_search, start)) >= 0) {
      result.push(this.slice(start, match));
      start = match + length;
    }
    result.push(this.slice(start));
  } else {
    result = this.split(search);
  }
  return result.join(replace);
}

用法:

alert('Bananas And Bran'.replaceAll('An', '(an)'));

String.prototype.replaceAll = function(character,replaceChar){
    var word = this.valueOf();

    while(word.indexOf(character) != -1)
        word = word.replace(character,replaceChar);

    return word;
}

我加了双反斜杠的点，使它工作。欢呼。

var st = "okay.this.is.a.string";
var Re = new RegExp("\\.","g");
st = st.replace(Re," ");
alert(st);

str.replace(new RegExp(".","gm")," ")