JavaScript 中的 Rest 和 Spread 運算子

Rest 運算子 (...) 允許我們使用任意數量的引數來呼叫一個函式，然後將這些多餘的引數作為陣列進行訪問。Rest 運算子還允許我們在解構陣列或物件時進行使用。

Spread運算子 (...) 允許我們將陣列等可迭代項擴充套件成其中的各個元素。

示例

以下是展示 JavaScript 中的 Rest 和 Spread 運算子的程式碼 −

<!DOCTYPE html>
<html lang="en" >
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
   body {
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   }
   .sample, .result {
      font-size: 20px;
      font-weight: 500;
   }
</style>
</head>
<body>
<h1>JavaScript Rest and spread operator</h1>
<div class="sample"></div>
<div style="color: green;" class="result"></div&g;
<button class="btn">Spread Operator</button>
<h3>
Click on the above button to concatenate array using spread operator
</h3>
<button class="btn">Rest Operator</button>
<div style="color: green;" class="result"></div>
<h3>
Click on the above button to add some numbers using rest operator
</h3>
<script>
   let sampleEle = document.querySelector(".sample");
   let btnEle = document.querySelectorAll(".btn");
   let resEle = document.querySelectorAll(".result");
   let arr = [2, 3, 4, 5];
   let arr1 = ["a", "b", "c", "d"];
   sampleEle.innerHTML = "arr = " + arr + "<br> arr1 = " + arr1;
   function addArr(num, ...ar) {
      let sum = num;
      ar.forEach((item) => {
         sum += item;
      });
      resEle[1].innerHTML = "Sum of the elements = " + sum;
   }
   btnEle[0].addEventListener("click", () => {
      resEle[0].innerHTML = "Concatenated array = " + [...arr, ...arr1];
   });
   btnEle[1].addEventListener("click", () => {
      addArr(44, 11, 35, 44, 22, 99);
   });
</script>
</body>
</html>