JS regex to match spaces and non-alphanumerics

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Javascript

regular-expression

I need a regex - well, two:
I want a JS regex to replace all whitespace with a hyphen

var str = 'some string';
var regex1 = ?????;
str = str.replace(regex1, '-');

and another to replace all non-alphanumerics with nothing - ie remove them

regex2 = ?????;
str = str.replace(regex2, '');

What I have tried:

Banging my head against a brick wall.
Wearing a garlic necklace.
I am armed with a wooden stake and a gun with a silver bullet.