Detailed explanation of HTML5 data-* custom attributes

In jQuery's attr and prop, it is mentioned that improper use of property in versions before IE9 will cause memory leaks, and the difference between Attribute and Property is also very troublesome. In HTML5, the data-* method is added to customize attributes. , the so-called data-* is actually the data- prefix plus a custom attribute name. Data can be stored using such a structure. Using data-* can solve the current situation of confusing and unmanaged custom attributes.

There are two setting methods for data-*, which can be written directly on HTML element tags.

 <div id=test data-age=24> Click Here </div>

The data-age is a custom attribute. Of course, we can also operate it through JavaScript. Elements in HTML5 will have a dataset attribute, which is a collection of key-value pairs of the DOMStringMap type.

 var test = document.getElementById('test'); test.dataset.my = 'Byron';

This adds a custom attribute of data-my to the div. There are two things to pay attention to when using JavaScript to operate the dataset.

1. We need to remove the prefix data-* when adding or reading attributes. Like the above example, we do not use the form test.dataset.data-my = 'Byron';.

2. If the attribute name also contains a hyphen (-), it needs to be converted to camel case naming. But if a selector is used in CSS, we need to use the hyphen format.

Add content to the code just now

 <style type=text/css> [data-birth-date] { background-color: #0f0; width:100px; margin:20px; } </style>

 test.dataset.birthDate = '19890615';

In this way, we set the data-birth-date custom attribute through JavaScript, and added some styles to the div in the CSS style sheet to see the effect.

When reading, it is also through the dataset object, using . to obtain the attributes. The data- prefix also needs to be removed, and the hyphens need to be converted into camel case naming.

 var test = document.getElementById('test'); test.dataset.my = 'Byron'; test.dataset.birthDate = '19890615'; test.onclick = function () { alert(this.dataset.my + ' ' + this.dataset.age+' '+this.dataset.birthDate); }

Some students may ask if there is any difference between this and getAttribute/setAttribute except naming. Let’s take a look.

 var test = document.getElementById('test'); test.dataset.birthDate = '19890615'; test.setAttribute('age', 25); test.setAttribute('data-sex', 'male'); console. log(test.getAttribute('data-age')); //24 console.log(test.getAttribute('data-birth-date')); //19890516 console.log(test.dataset.age); //24 console.log(test.dataset.sex); //male

From this we can see that both of them set attributes to attributes (nonsense, otherwise they can be called custom attributes), which means that getAttribute/setAttribute can operate on all dataset contents, and dataset contents are only a subset of attributes. The special thing is the naming, but there are only attributes with the data- prefix in the dataset (there is no age=25 one).

So why do we still use data-*? One of the biggest advantages is that we can manage all custom attributes in a unified manner in the dataset object. It is very convenient to traverse everything without being scattered, so It's still good to use.

The bad news is that the browser compatibility of data-* is very pessimistic.

1. Internet Explorer 11+
2. Chrome 8+
3. Firefox 6.0+
4. Opera 11.10+
5. Safari 6+

Among them, IE11+ is simply blinding the eyes of my friends. It seems that there is a long way to go to fully use this attribute.

The above is the entire content of this article. I hope it will be helpful to everyone’s study. I also hope everyone will support VeVb Wulin Network.