使用javascript清理文本

I have been using 2 php functions to clean some texts (file names) and prepare them for being post titles or tags. I need to do the same functions using Javascript but I don't know the alternatives in Javascript or their syntax. I anyone experienced in Javascript and PHP can do this conversion.

First php Function:

function maketitle($str)
{
    $str = preg_replace('/[^A-Za-z]/', ' ', $str);
    $str = str_replace(' jpg', '', $str);
    $str = str_replace(' gif', '', $str);
    $str = str_replace(' jepg', '', $str);
    $str = str_replace(' png', '', $str);
    $str = trim($str);
    return $str;
}

Second PHP function:

maketags($str)
{
    $str = implode(", ", preg_split("/[\s]+/", $str));;
    return $str;
}

Thanks in advance.
Best Regards

You can use a lot of the default built in Javascript string functions. See the left side of this page for links to more. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace

function maketitle(str) {
  return str.replace(/[^A-Za-z]/, ' ')
    .replace(' jpg', '')
    .replace(' gif', '')
    .replace(' jepg', '')
    .replace(' png', '')
    .trim();
}

function maketags(str) {
 return str.split(/[\s]+/).join(", ");
}

Here is a jsbin of the working code. http://jsbin.com/tulemi/1/edit?html,js,console