javascript 如何在 Chrome 中检查 input type="date" 的（空）值
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How to check the (empty) value of a input type="date" in Chrome
提问by Kanye West
I want to check if the user entered a date. But I can't figure it out how to do it.
我想检查用户是否输入了日期。但我不知道该怎么做。
Here's some javascript code what i already got but doesn't work :
这是我已经得到但不起作用的一些 javascript 代码：
var valueDate = document.getElementById('Date').value;
if ( valueDate== null || valueDate== '')
{
alert('Date is empty');
return false;
}
And the HTML <input type="date" name="Date" id="Date"/>Thanks in advance!
和 HTML<input type="date" name="Date" id="Date"/>提前致谢！
回答by Marius Schulz
You could check for a falsy value:
你可以检查一个假值：
if (!valueDate) {
// ...
}
The six falsy values of JavaScript are
JavaScript 的六个假值是
undefined,null,false,- the empty string,
0(of typenumber), andNaN.
undefined,null,false,- 空字符串，
0（类型number），和NaN.
Since document.getElementById('Date').valueis always of type string if a value is set, you don't get false positives like 0being treated like no input, which would be the case if the type was number.
由于document.getElementById('Date').value如果设置了值，则始终为字符串类型，因此您不会得到误报，例如0被视为没有输入，如果类型为number.
回答by Tr1stan
I would try using Date.parse() if I were you.
如果我是你，我会尝试使用 Date.parse()。
var valueDate = document.getElementById('Date').value;
if(!Date.parse(valueDate)){
alert('date is invalid');
}
