Regex to replace multiple spaces with a single space

Here is an alternate solution if you do not want to use replace (replace spaces in a string without using replace javascript)

var str="The dog      has a long   tail, and it     is RED!";
var rule=/\s{1,}/g;

str = str.split(rule).join(" "); 

document.write(str);

More robust:

function trim(word)
{
    word = word.replace(/[^\x21-\x7E]+/g, ' '); // change non-printing chars to spaces
    return word.replace(/^\s+|\s+$/g, '');      // remove leading/trailing spaces
}

var string = "The dog      has a long   tail, and it     is RED!";
var replaced = string.replace(/ +/g, " ");

Or if you also want to replace tabs:

var replaced = string.replace(/\s+/g, " ");