HTMLElement.dataset

Właściwość dataset interfejsu HTMLElement pozwala na odczyt/zapis niestandardowcyh atrybutów (data-*) elementu. Dostęp ten jest możliwy w HTMLu jak i w DOMie.  It is a map of DOMString, one entry for each custom data attribute. Zauważ że właściwość dataset można odczytać, ale nie zmieniać bezpośrednio. Zamiast tego, wszystkie zapisy muszą być wykonywane na pojedynczych polach dataset, które odpowiadają atrybutom danych. Note also that an HTML data-attribute and its corresponding DOM dataset.property do not share the same name, but they are always similar:

  • The name of a custom data attribute in HTML begins with data-. It must contain only letters, numbers and the following characters: dash (-), dot (.), colon (:), underscore (_) -- but NOT any ASCII capital letters (A to Z).
  • The name of a custom data attribute in JavaScript is the name of the same HTML attribute but in camelCase and with no dashes, dots, etc.

In addition to the information below, you'll find a how-to guide for using HTML data attributes in our article Using data attributes.

Zmiana nazw

dash-style to camelCase: A custom data attribute name is transformed to a key for the DOMStringMap entry with the following rules

  • the prefix data- is removed (including the dash);
  • for any dash (U+002D) followed by an ASCII lowercase letter a to z, the dash is removed and the letter is transformed into its uppercase counterpart;
  • other characters (including other dashes) are left unchanged.

camelCase to dash-style: The opposite transformation, that maps a key to an attribute name, uses the following rules:

  • Restriction: A dash must not be immediately followed by an ASCII lowercase letter a to z (before the transformation);
  • a prefix data- is added;
  • any ASCII uppercase letter A to Z is transformed into a dash followed by its lowercase counterpart;
  • other characters are left unchanged.

The restriction in the rules above ensures that the two transformations are the inverse one of the other.

For example, the attribute named data-abc-def corresponds to the key abcDef.

Dostęp do wartości

  • Attributes can be set and read by using the camelCase name (the key) like an object property of the dataset, as in element.dataset.keyname
  • Attributes can also be set and read using the object-properties bracket-syntax, as in element.dataset[keyname]
  • The in operator can be used to check whether a given atttribute exists.

 

Ustawianie wartości

  • When an attribute is set, it's value is always converted into a string. For example null is converted into the string "null".
  • When you want to remove an attribute, you can use the delete operator.

Składnia

  • string = element.dataset.camelCasedName;
  • element.dataset.camelCasedName = string;

  • string = element.dataset[camelCasedName];
  • element.dataset[camelCasedName] = string;

  • Custom data attributes can also be set directly on HTML elements, but attribute names must use the data- syntax above.

Przykłady

<div id="user" data-id="1234567890" data-user="johndoe" data-date-of-birth>John Doe</div>
const el = document.querySelector('#user');

// el.id == 'user'
// el.dataset.id === '1234567890'
// el.dataset.user === 'johndoe'
// el.dataset.dateOfBirth === ''

// set the data attribute
el.dataset.dateOfBirth = '1960-10-03'; 
// Result: el.dataset.dateOfBirth === 1960-10-03

delete el.dataset.dateOfBirth;
// Result: el.dataset.dateOfBirth === undefined

// 'someDataAttr' in el.dataset === false
el.dataset.someDataAttr = 'mydata';
// Result: 'someDataAttr' in el.dataset === true

Specyfikacje

Specyfikacja Status Komentarz
HTML Living Standard
The definition of 'HTMLElement.dataset' in that specification.
Living Standard No change from latest snapshot, HTML 5.1
HTML 5.1
The definition of 'HTMLElement.dataset' in that specification.
Recommendation Snapshot of HTML Living Standard, no change from HTML5
HTML5
The definition of 'HTMLElement.dataset' in that specification.
Recommendation Snapshot of  HTML Living Standard, initial definition.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
datasetChrome Full support 8Edge Full support 12Firefox Full support 6IE Full support 11Opera Full support 11Safari Full support 10WebView Android Full support 4.4Chrome Android Full support 18Firefox Android Full support 6Opera Android Full support YesSafari iOS Full support YesSamsung Internet Android ?

Legend

Full support  
Full support
Compatibility unknown  
Compatibility unknown

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