如何将HTML中的Javascript事件处理程序内联转换为要参数化的？
[英]How do I convert a Javascript event handler inline in HTML to be parameterized?
问题描述
Quick javascript question. 
快速的JavaScript问题。 I am creating a simple script where a form field entry disappears/reappears using onfocus and onblur. 我正在创建一个简单的脚本，其中使用onfocus和onblur在表单字段条目消失/重新出现。
I'm wondering why the following inline script works: 我想知道为什么以下内联脚本有效：
<div>
<input type="text" name="email" id="email" value="Requires validation"
onfocus="if(this.value == 'Requires validation'){this.value = '';}"
onblur="formappear()">
</div>
and the following script with a parameterized function doesn't: 而以下带有参数化功能的脚本则没有：
<head>
<script type='text/javascript'>
function formclear(field) {
if (field.value == "Requires validation") {
field.value = "";
}
}
</script>
</head>
<body>
<div>
<input type="text" name="email" id="email" value="Requires validation"
onfocus="formclear(this.id)" onblur="formappear()">
</div>
</body>
I appreciate any responses in advance, I'm sure it's a simple mistake I'm making. 感谢您提前做出的任何回应，我敢肯定这是我犯的一个简单错误。
3 个解决方案
解决方案1
1 已采纳 2013-05-28 17:22:02
Dont pass in this.id , just pass in this 不要传递this.id ，只需传递this
<input type="text" name="email" id="email" value="Requires validation" onfocus="formclear(this)" onblur="formappear()">
Demo: http://jsfiddle.net/se6wm/ 演示： http ： //jsfiddle.net/se6wm/
You were passing in the id of the input, so when you were using field.value it was actually trying to do email.value which doesn't exist. 您正在传递输入的id ，因此当您使用field.value它实际上是在尝试执行不存在的email.value 。
解决方案2
0 2013-05-28 17:22:10
因为您传递的是id而不是this
解决方案3
0 2013-05-28 17:23:30
pass a value as formclear(this) instead of formclear(this.id) 将值传递为formclear(this)而不是formclear(this.id)
<input type="text" name="email" id="email" value="Requires validation"
onfocus="formclear(this)" onblur="formappear()">
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