Linter Rule: Disallow ERB silent tags in HTML attribute names

Rule: erb-no-silent-tag-in-attribute-name

Description

Disallow the use of ERB silent tags (<% ... %>) inside HTML attribute names. These tags introduce Ruby logic that does not output anything, and placing them in attribute names leads to malformed HTML or completely unpredictable rendering.

Rationale

HTML attribute names, ideally, must be valid, statically defined strings. Placing ERB silent tags (<% ... %>) that don't output anything inside attribute names might result in invalid HTML and is confusing. These cases are rarely intentional and almost always indicate a mistake or misuse of ERB templating.

Examples

✅ Good

<div data-<%= key %>-target="value"></div>
Avoid ERB output in attribute names. Use static attribute names with dynamic values instead. (erb-no-output-in-attribute-name)
<div <%= data_attributes_for(user) %>></div>
Avoid `<%= %>` in attribute position. Use `<% if ... %>` with static attributes instead. (erb-no-output-in-attribute-position)

🚫 Bad

<div data-<% key %>-id="value"></div>
Remove silent ERB tag from HTML attribute name. Silent ERB tags (`<%`) do not output content and should not be used in attribute names. (erb-no-silent-tag-in-attribute-name)
Avoid unused expressions in silent ERB tags. `key` is evaluated but its return value is discarded. Use `<%= ... %>` to output the value or remove the expression. (erb-no-unused-expressions)

<div data-<%# key %>-id="thing"></div>
Remove silent ERB tag from HTML attribute name. Silent ERB tags (`<%#`) do not output content and should not be used in attribute names. (erb-no-silent-tag-in-attribute-name)

<div data-<%- key -%>-id="thing"></div>
Remove silent ERB tag from HTML attribute name. Silent ERB tags (`<%-`) do not output content and should not be used in attribute names. (erb-no-silent-tag-in-attribute-name)
Avoid unused expressions in silent ERB tags. `key` is evaluated but its return value is discarded. Use `<%= ... %>` to output the value or remove the expression. (erb-no-unused-expressions)

References

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