>展開語法(Spread syntax), 可以在函數調用/數組構造時, 將數組表達式或者string在語法層面展開；還可以在構造字面量對象時, 將對象表達式按key-value的方式展開。(譯者注: 字面量一般指 [1, 2, 3] 或者 {name: "mdn"} 這種簡潔的構造方式) ~~~ function sum(x, y, z) { return x + y + z; } const numbers = [1, 2, 3]; console.log(sum(...numbers)); // expected output: 6 console.log(sum.apply(null, numbers)); // expected output: 6 ~~~ 數組展開 ~~~ var arr=[1,2,3]; console.log(...arr); ~~~ >## 語法 函數調用： ~~~ myFunction(...iterableObj); ~~~ 字面量數組構造或字符串 ~~~ var arr0 = [1,2,3] var arr=[...arr0,..."hello"]; console.log(arr); ~~~ 構造字面量對象時,進行克隆或者屬性拷貝 語法 ~~~ let objClone = { ...obj }; ~~~ ~~~ var obj = { name:"cheng", age:20 } var zhang = {...obj}; console.log(zhang); ~~~ ~~~ var parts = ['shoulders'，'knees']; var lyrics = ['head'，... parts，'and'，'toes']; // ["head", "shoulders", "knees", "and", "toes"] ~~~ [mozllia文檔](https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Operators/Spread_syntax#%E8%AF%AD%E6%B3%95)