• 默認(rèn)值傳參

function fn(x, y = 1) {
            console.log(y);
        }
        fn(100);

• 形參賦值結(jié)合解構(gòu)賦值

 function fn({ x, y=100 }) {
            console.log(x, y);
        }
        fn({ x: 1});//1,100

• 剩余運(yùn)算符

  function sum(...a){
            console.log(a);
        }
        sum(1,2,3,4,5)//12345