Converts a string to constant case.
string to convert
a constant-cased string
var str = constantcase( 'beep' ); // returns 'BEEP'
var str = constantcase( 'beep boop' ); // returns 'BEEP_BOOP'
var str = constantcase( 'Hello World!' ); // returns 'HELLO_WORLD'
Converts a string to constant case.