[英]I don't understand jQuery.data() method
.data()-Attaches
data to, or gets data from, selected elements. .data()-Attaches
数据.data()-Attaches
到选定元素或从中获取数据。 A method in jQuery jQuery中的方法
Question: 题:
1) What the purpose of this method ? 1)这种方法的目的是什么?
2) When I run it, I see NO data-* attribute created. 2)运行它时,我看不到创建了data- *属性。 So what is the difference between data-*
attribute and data created by data()
method in jQuery? 那么data-*
属性和jQuery中data()
方法创建的data()
什么区别?
<!--code from w3school -->
<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script>
$(document).ready(function(){
$("#btn1").click(function(){
$("div").data("greeting", "Hello World");
});
$("#btn2").click(function(){
alert($("div").data("greeting"));
});
});
</script>
</head>
<body>
<button id="btn1">Attach data to div element</button><br>
<button id="btn2">Get data attached to div element</button>
<div></div>
</body>
</html>
One use case can be around storing instance, pseudo code below 一种用例可以是围绕存储实例,下面是伪代码
function SomePlugin(element, options) {
this.$el = $(element);
this.options = options;
}
SomePlugin.prototype.method = function() {
this.$el.toggleClass(this.options.cssClass);
}
$.fn.somePlugin = function(options) {
var somePluginInstance = new SomePlugin(this, options);
// store instance as data
this.data("somePlugin", somePluginInstance);
}
usage: 用法:
$(".element").somePlugin({});
var pluginInstance = $(".element").data("somePlugin");
pluginInstance.method();
The .data() method allow you to attach data of any type of DOM elements in a way that is safe from circular references and therefore from memory leaks. .data()方法允许您以一种安全的方式附加任何类型的DOM元素的数据,以防止循环引用,从而避免内存泄漏。
We can set several distinct values for a single element and retrieve them later: (Documentation example) 我们可以为单个元素设置几个不同的值,然后在以后检索它们:(文档示例)
$( "body" ).data( "foo", 52 );
$( "body" ).data( "bar", { isManual: true } );
$( "body" ).data( { baz: [ 1, 2, 3 ] } );
$( "body" ).data( "foo" ); // 52
$( "body" ).data(); // { foo: 52, bar: { isManual: true }, baz: [ 1, 2, 3 ] }
"Using the data() method to update data does not affect attributes in the DOM. To set a data-* attribute value, use attr. “使用data()方法更新数据不会影响DOM中的属性。要设置data- *属性值,请使用attr。
Prior to jQuery 1.4.3, .data( obj ) completely replaced all data. 在jQuery 1.4.3之前,.data(obj)完全替换了所有数据。 Since jQuery 1.4.3, data is instead extended by shallow merge." 从jQuery 1.4.3开始,数据通过浅合并来扩展。”
font: jquery documentation 字体:jquery文档
:) :)
Regarding HTML5 data-* attributes: This low-level method does NOT retrieve the data-* attributes unless the more convenient .data() method has already retrieved them. 关于HTML5 data- *属性:除非更方便的.data()方法已检索到data- *属性,否则此低级方法不会检索到data- *属性。
The jQuery.data() method allows us to attach data of any type to DOM elements in a way that is safe from circular references and therefore from memory leaks. jQuery.data()方法允许我们以一种安全的方式将任何类型的数据附加到DOM元素上,从而避免循环引用,从而避免内存泄漏。 We can retrieve several distinct values for a single element one at a time, or as a set. 我们可以一次或作为一组检索单个元素的多个不同值。
You can refer this link for more details. 您可以参考此链接以获取更多详细信息。 I hope this can help you. 希望对您有所帮助。
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