包含空字符串的HTML属性不显示=运算符 [英] Html attribute containing empty string doesn't show = operator

问题描述

一个用例是在jQuery中:

One use case is in jQuery:

 $select.append('<option value="">All</option>');

看起来它实际上在HTML中添加了元素:

It looks like it actually adds the element in HTML:

<option value>All</option>

相反，我要附加到元素上，以便为值提供一个空字符串:

Instead, what I want is to append to the element so that it gives an empty string to value:

<option value="">All</option>

为什么那不会发生?

推荐答案

它实际上在HTML中添加了元素

It actually add the element in HTML

不，不是.

它将元素添加到DOM，而不是HTML.

It adds the element to the DOM, not to the HTML.

使用浏览器的开发人员工具查看DOM时，它将使用类似HTML的语法显示.使用这种语法，将呈现一个 value 属性，该值是一个空字符串，而不包含 =" 部分.(看起来该语法的一部分实际上是有效的HTML，但是我在规范中没有找到允许该部分的部分.)

When you look at the DOM, using your browser's developer tools, it will displayed using HTML-like syntax. In this syntax, a value attribute where the value is an empty string will be rendered without the ="" portion. (It is looking like that part of the syntax is actually valid HTML, but I haven't found the part in the spec which allows it.)

如果您使用的是Chrome浏览器(以Chrome为例)，则可以右键单击其父元素，然后选择以HTML格式编辑"，此时您将再次看到 =" .

If you were (to use Chrome as an example), you could right click on its parent element and pick "Edit as HTML" at which point you would see the ="" again.

如果要提交包含select元素的表单，您将看到发送的数据为: select_name = .这表明该值已正确设置为空字符串.如果不起作用，您将得到 select_name = All ，因为如果未设置任何值，则将元素的文本用作值.

If you were to submit the form containing the select element you would see that the data sent would be: select_name=. This shows that the value was correctly set to an empty string. If it had not worked you would have got select_name=All since the element's text is used as the value if no value is set.

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