1.初学js, 用Dom操作html的时候,js中的函数不生效. 两种解决方法都可以解决问题,但是不明白原因.
谢谢
2.错误代码, 函数放在最后不生效
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
div {
height: 22px;
width: 300px;
background-color: #ccc;
}
</style>
</head>
<body>
<button>显示系统时间</button>
<div>时间</div>
<script>
var btn = document.getElementsByTagName('button')
btn[0].onclick = function () {
btn[0].innerText = getDate()
}
var div = document.getElementsByTagName('div')
div[0].innerText = getDate()
var getDate = function () {
var date = new Date();
var year = date.getFullYear();
var month = date.getMonth() + 1;
var dates = date.getDate();
var day = date.getDay()
var Day = ['星期天', '星期一', '星期二', '星期三', '星期四', '星期五', '星期六']
var hour = date.getHours()
var minute = date.getMinutes()
var second = date.getSeconds()
return year + '年' + month + '月' + dates + '日' + Day[day] + hour + '时' + minute + '分' + second + '秒';
}
</script>
</body>
3.解决方法(一)
var btn = document.getElementsByTagName('button');
btn[0].onclick = function () {
btn[0].innerText = getDate()
}
var getDate = function () {
var date = new Date();
var year = date.getFullYear();
var month = date.getMonth() + 1;
var dates = date.getDate();
var day = date.getDay()
var Day = ['星期天', '星期一', '星期二', '星期三', '星期四', '星期五', '星期六']
var hour = date.getHours()
var minute = date.getMinutes()
var second = date.getSeconds()
return year + '年' + month + '月' + dates + '日' + Day[day] + hour + '时' + minute + '分' + second + '秒';
}
var div = document.getElementsByTagName('div');
div[0].innerText = getDate();
解决方法(二)
var btn = document.getElementsByTagName('button');
btn[0].onclick = function () {
btn[0].innerText = getDate()
}
var div = document.getElementsByTagName('div');
div[0].innerText = getDate();
var getDate = function () {
var date = new Date();
var year = date.getFullYear();
var month = date.getMonth() + 1;
var dates = date.getDate();
var day = date.getDay()
var Day = ['星期天', '星期一', '星期二', '星期三', '星期四', '星期五', '星期六']
var hour = date.getHours()
var minute = date.getMinutes()
var second = date.getSeconds()
return year + '年' + month + '月' + dates + '日' + Day[day] + hour + '时' + minute + '分' + second + '秒';
}
