let leven = ( a , b ) => 0 ; if ( process . env . NODE_ENV !== 'production' ) { const arr = [ ] ; const charCodeCache = [ ] ; leven = ( a , b ) => { if ( a === b ) return 0 ; const aLen = a . length ; const bLen = b . length ; if ( aLen === 0 ) return bLen ; if ( bLen === 0 ) return aLen ; let bCharCode ; let ret ; let tmp ; let tmp2 ; let i = 0 ; let j = 0 ; while ( i < aLen ) { charCodeCache [ i ] = a . charCodeAt ( i ) ; arr [ i ] = ++ i ; } while ( j < bLen ) { bCharCode = b . charCodeAt ( j ) ; tmp = j ++ ; ret = j ; for ( i = 0 ; i < aLen ; i ++ ) { tmp2 = bCharCode === charCodeCache [ i ] ? tmp : tmp + 1 ; tmp = arr [ i ] ; ret = arr [ i ] = tmp > ret ? ( tmp2 > ret ? ret + 1 : tmp2 ) : tmp2 > tmp ? tmp + 1 : tmp2 ; } } return ret ; } ; } export default leven ;