Description
Audit a deliberately restricted ASCII custom-property token grammar -- followed by letters/digits/underscore/dash; not full CSS identifier validation.
CSS combines token syntax, property-specific value rules and layout/cascade processing. These are separate layers: splitting a declaration does not establish that its value is valid, and arithmetic on resolved lengths does not perform browser layout. Each tool here handles an explicit numeric representation or a stated lexical subset.
Audit a deliberately restricted ASCII custom-property token grammar -- followed by letters/digits/underscore/dash; not full CSS identifier validation.
When to use this tool
Use this tool to audit a deliberately restricted ASCII custom-property token grammar -- followed by letters/digits/underscore/dash; not full CSS identifier validation.
How to use the tool and how it works
- Enter name using the input definitions below.
- Run the operation. Resolve malformed-input errors before interpreting the result.
- Read result.valid. Interpret signs, units, ordering and null values using the rules below.
Return valid = true only for the complete token -- followed by one or more ASCII letters, digits, underscores or hyphens.1, 2
| Input field | Meaning and units | Accepted input |
|---|---|---|
| name | Custom-property token to audit using the stated restricted ASCII grammar. | Text, at most 8,192 UTF-16 code units; the stated grammar and narrower limits also apply. |
| Output field | Interpretation |
|---|---|
| result | Object containing the fields below. |
| result.valid | Whether the complete custom-property token matches the restricted ASCII grammar. |
{
"input": {
"name": "--x"
},
"output": {
"result": {
"valid": true
}
}
}Limitations and assumptions
- A false result can be valid CSS outside this intentionally restricted ASCII grammar; this is not complete identifier validation.
- Lengths and times must already be resolved to consistent numeric units. Lexical helpers intentionally support smaller grammars than a full browser CSS parser; malformed supported-subset input causes an error.
- Every declared top-level input is required and unknown fields are rejected. Ordinary strings are limited to 8,192 UTF-16 code units and lists to 128 entries, with tighter operation-specific bounds where stated. JSON text has bounded nesting and node counts.
- Numeric outputs must be finite and within the absolute safe-integer magnitude; exact larger integers use decimal text. Source positions are zero-based UTF-16 offsets and span ends are exclusive unless a different convention is explicitly stated.
Alternative or Complementary methods
Use a full CSS parser or browser style/layout APIs when escape handling, error recovery, computed styles or the full cascade matter. These tools expose focused transformations and audits of supplied data.
References
Similar or alternative tools
- CSS Custom Property Reference Inventory
Inventory unescaped ASCII var() reference names including nested fallbacks, ignoring quoted strings; existing variable-parser extracts declarations instead. Comment-free balanced CSS subset.
- CSS Identifier Escape Token Decoder
Decode CSS identifier escape sequences to Unicode scalars with replacement for zero/surrogate/out-of-range code points; requires an already isolated identifier token, not full identifier grammar.