export function test1 ( _x , y ) { console . log ( y ) ; } export function test2 ( x , _y ) { console . log ( x ) ; } export function test3 ( props ) { const { x , ... rest } = props ; console . log ( rest ) ; } export function test4 ( ) { try { throw new Error ( 'xxx' ) ; } catch ( e ) { console . log ( '出错了' ) ; } }