定义和用法
forEach() 方法用于调用数组的每个元素，并将元素传递给回调函数。
注意: forEach() 对于空数组是不会执行回调函数的。
语法
array.forEach(function(currentValue, index, arr), thisValue)
实例
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<script type="text/javascript">
[1, 2, 3, 4, 5].forEach(function(a) {
console.log(a, this)
})
</script>
<script type="text/javascript">
[1, 2, 3, 4, 5].forEach(function(a) {
console.log(a, this)
}, [6, 7, 8, 9])
</script>
<script type="text/javascript">
Array.prototype.forEach.call([1, 2, 3, 4, 5], function(a) {
console.log(a, this)
}, [6, 7, 8, 9])
</script>
<script type="text/javascript">
Array.prototype.forEach.apply([1, 2, 3, 4, 5], [function(a) {
console.log(a, this)
},
[6, 7, 8, 9]
])
</script>
<script type="text/javascript">
Array.prototype.forEach.bind([1, 2, 3, 4, 5])(function(a) {
console.log(a, this)
}, [6, 7, 8, 9])
</script>
</head>
<body>
</body>
</html>
