<html><head><meta charset="utf-8"><title>手册网教程(shouce.ren)</title></head><body><p>点击按钮计算数组所有元素相加的总和。</p><button onclick="numbers.forEach(myFunction)">点我</button><p>数组元素总和：<span id="demo"></span></p><script>var sum = 0;var numbers = [65, 44, 12, 4];function myFunction(item) { sum += item; demo.innerHTML = sum;}</script></body></html>