Description
Parse one restricted CSS declaration, respecting quoted/parenthesized colons and terminal important; comments and escaped property names are rejected.
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.
Parse one restricted CSS declaration, respecting quoted/parenthesized colons and terminal important; comments and escaped property names are rejected.
When to use this tool
Use this tool to parse one restricted CSS declaration, respecting quoted/parenthesized colons and terminal important; comments and escaped property names are rejected.
How to use the tool and how it works
- Enter declaration using the input definitions below.
- Run the operation. Resolve malformed-input errors before interpreting the result.
- Read result.name, result.value, result.important. Interpret signs, units, ordering and null values using the rules below.
Parse one nonempty declaration using balanced lexical splitting, take the first top-level colon as the separator, normalize the property name, and strip a recognized terminal !important suffix into a boolean flag. Require exactly one declaration.1, 2
| Input field | Meaning and units | Accepted input |
|---|---|---|
| declaration | One complete declaration in the supported comment-free balanced subset. | 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.name | Normalized property name; custom-property casing is preserved. |
| result.value | Parsed or formatted CSS-subset value string. |
| result.important | Whether a terminal top-level importance annotation was recognized. |
{
"input": {
"declaration": "Color:rgb(1,2,3) !important"
},
"output": {
"result": {
"name": "color",
"value": "rgb(1,2,3)",
"important": true
}
}
}Limitations and assumptions
- Comments and escaped property identifiers are rejected; successful splitting does not prove that the value is valid for the property.
- 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 Name Token Audit
Audit a deliberately restricted ASCII custom-property token grammar -- followed by letters/digits/underscore/dash; not full CSS identifier validation.
- CSS Duplicate Property Table
Audit declaration property duplicates with ordinary ASCII property folding and case-sensitive custom-property names; not a cascade engine.