第一题：
<!DOCTYPE html>
<html>
<head><title>计算奇数和</title>
</head>
<body><label for="input">请输入一个正整数：</label><input type="number" id="input"><button onclick="calculate()">计算</button><p id="result"></p><script>function calculate() {let input = parseInt(document.getElementById("input").value);let result = 0;for (let i = 1; i <= input; i += 2) {result += i;}document.getElementById("result").innerHTML = `1 + 3 + 5 + ... + ${input} = ${result}`;}</script>
</body>
</html>
运行结果：
第二题：
<!DOCTYPE html>
<html>
<head><title>计算1 ~ 100的和</title>
</head>
<body><button onclick="displayResult()">计算</button><p id="result"></p><script>function calculateSum(num) {if (num === undefined) {num = 1; // 默认从 1 开始}if (num > 100) {return 0; // 递归终止条件}return num + calculateSum(num + 1); // 递归调用}function displayResult() {document.getElementById("result").innerHTML = `1 + 2 + 3 + ... + 100 = ${calculateSum()}`;}</script>
</body>
</html>
运行结果：
