JQuery .data() 不起作用？
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JQuery .data() not working?
提问by user1143682
Recently I was coding away, and I ran into a weird issue. I was attempting to assign a data attribute to a new element I had created (via jQuery), only to discover it wouldn't actually assign the attribute. See the link below for an example, the code is listed below:
最近我在写代码，遇到了一个奇怪的问题。我试图将数据属性分配给我创建的新元素（通过 jQuery），结果发现它实际上并没有分配该属性。示例见下面链接，代码如下：
http://jsfiddle.net/y95p100c/1/
http://jsfiddle.net/y95p100c/1/
Any idea why this is happening? I've never stumbled into this...
知道为什么会这样吗？我从来没有偶然发现这个......
var div = $("<div />")
$(div).data("foo", "bar")
console.log($(div)[0].outerHTML) // prints <div></div>
回答by T.J. Crowder
datadoesn't setdata-*attributes. It manages a data cache unrelated to data-*attributes. It initializesfrom data-*attributes if there are any present, but never writes to them. To write to an attribute, use attr.
data不设置data-*属性。它管理与data-*属性无关的数据缓存。如果存在任何属性，它将从属性初始化data-*，但从不写入它们。要写入属性，请使用attr.
Example: Updated Fiddle
示例：更新的小提琴
var div = $("<div />")
$(div).attr("data-foo", "bar")
console.log($(div)[0].outerHTML)
What you're seeing is just one of the many ways this can be surprising. Another is that if your markup is <div id="elm" data-foo="bar"></div>and at some point you use $("#elm").data("foo")to get the value (and it will indeed be "bar"), then you do $("#elm").data("foo", "update"), the attribute remains data-foo="bar"but the data managed by datanow has fooequal to "update". But the rule above explains it: datanever writesto data-*attrs.
您所看到的只是令人惊讶的众多方式之一。另一个是，如果您的标记是，<div id="elm" data-foo="bar"></div>并且在某些时候您$("#elm").data("foo")用来获取值（并且确实会是"bar"），那么您这样做了$("#elm").data("foo", "update")，属性仍然存在，data-foo="bar"但data现在管理的数据foo等于"update"。但上面的规则解释它：data从来没有写入到data-*ATTRS。
回答by lonesomeday
jQuery imports the data-attributes when the element is loaded, but does not access it afterwards. The elements are stored in a jQuery internal structure. From the API:
jQuerydata-在元素加载时导入属性，但之后不会访问它。元素存储在 jQuery 内部结构中。从API：
The
data-attributes are pulled in the first time the data property is accessed and then are no longer accessed or mutated (all data values are then stored internally in jQuery).
的
data-属性被拉到在第一时间中的数据属性被访问，然后不再访问或突变的（所有数据值然后被存储在内部的jQuery）。
