A brief analysis of using data-* to customize attributes in HTML5

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. HTML5 adds the data-* method to customize attributes. The so-called data-* is actually the data- prefix plus a custom attribute name. This structure can be used to store data. Using data-* can solve the current situation of confusing and unmanaged custom attributes.

Reading and writing methods

data-*There are two setting methods, you can write directly on the HTML element tag

<div>
        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';

In this way, a data-my is added to p There are two things you need to pay attention to when using JavaScript to operate datasets for custom attributes

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

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

as just now The code appends the content

<style>
        [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, add some styles to p in the CSS style sheet, and 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);
        }

getAttribute/setAttribute

Some students may ask if there is any difference between this and getAttribute/setAttribute besides 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

In this way we can see that both of them set attributes to attributes (nonsense, otherwise they can call them custom attributes), that is to say getAttribute/setAttribute All dataset contents can be operated. The dataset contents are only a subset of attributes. The special thing is the naming. However, there are only attributes with 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 going to zero. It’s scattered, so it’s still good to use.

Browser compatibility

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

• Internet Explorer 11
• Chrome 8
• Firefox 6.0
• Opera 11.10
• Safari 6

Among them, IE11 is simply blinding my friends. It seems that There is a long way to go to fully use this attribute

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