js，求一条正则该怎么写

Question

'160px'.replace(/xxx/,'') => '160'
'160.66px'.replace(/xxx/,'') => '160'

求解一条正则上面两种情况都能满足

Answer 1

// => 160
'160px'.replace(/(^\d+)(.*)/, '$1')

// => 160
'160.66pxpx'.replace(/(^\d+)(.*)/, '$1')

Answer 2

/(.d+)*px$/

Answer 3

'160px'.replace(/[\.|p](\S*)x/, '')

Answer 4

str.match(/^\d+/)[0];