1:reduce应用场景:计算数组中所有值的总和 数组求和:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
</body>
<script>
//一堆变成一个,算总数
let arr = [12, 33, 66, 99]
let result = arr.reduce(function(tmp, item, index) {
return tmp + item
})
console.log(result);
</script>
</html>
打印结果如下:
2:forEach循环遍历(迭代)
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
</body>
<script>
let arr = [12, 4, 6, 89, 2]
arr.forEach(item => {
console.log(item)
})
</script>
</html>
打印结果如下:
参数index
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
</body>
<script>
let arr = [12, 4, 6, 89, 2]
//参数index
arr.forEach((item,index) => {
console.log(index+ ':' +item)
})
</script>
</html>
打印结果如下: