CODEWITHSUNDEEP
javascriptdomattributesdataset
David Spector
David Spector

Reputation: 1671

Data-name (dataset) attribute not reported correctly

I created a custom dataset attribute on an element node (El.dataset.FTid=i;), where i is a number, but when I use (El.attributes) to look at it, the attribute name is reported as (data--f-tid) instead of (data-FTid) as expected. Very strange! Firefox 63.0.3 (64bit).

Upvotes: 0

Views: 69

Answers (1)

Jeto
Jeto

Reputation: 14927

When setting properties of the dataset collection of a DOM element, they will automatically be converted to the corresponding attribute names following these rules:

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.

In your case, you should probably use:

El.dataset.ftId = i;

which will be accessible via:

El.getAttribute('data-ft-id')

Upvotes: 1

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