Replace all non Alpha Numeric characters, New Lines, and multiple White Space with one Space
Be aware, that \W leaves the underscore. A short equivalent for [^a-zA-Z0-9] would be [\W_]
text.replace(/[\W_]+/g," ");\W is the negation of shorthand \w for [A-Za-z0-9_] word characters (including the underscore)
Jonny 5 beat me to it. I was going to suggest using the \W+ without the \s as in text.replace(/\W+/g, " "). This covers white space as well.
Since [^a-z0-9] character class contains all that is not alnum, it contains white characters too!
text.replace(/[^a-z0-9]+/gi, " ");