@wix/css-property-parser
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A comprehensive TypeScript library for parsing and serializing CSS property values with full MDN specification compliance
73 lines (72 loc) • 2.52 kB
JavaScript
// Letter Spacing property parser
// Handles parsing of CSS letter-spacing property values
// https://developer.mozilla.org/en-US/docs/Web/CSS/letter-spacing
import { isGlobalKeyword, isCssVariable, getValidKeyword } from '../utils/shared-utils.js';
import { parse as parseCSSVariable, toCSSValue as cssVariableToCSSValue } from './css-variable.js';
import { parse as parseLength, toCSSValue as lengthToCSSValue } from './length.js';
// Import centralized types
import { LETTER_SPACING_KEYWORDS } from '../types.js';
/**
* Parse a CSS letter-spacing property string
*/
export function parse(value) {
if (!value || typeof value !== 'string') {
return null;
}
const trimmed = value.trim();
if (trimmed === '') {
return null;
}
// CSS variables - parse and return directly
if (isCssVariable(trimmed)) {
return parseCSSVariable(trimmed);
}
// Handle global keywords
if (isGlobalKeyword(trimmed)) {
return { type: 'keyword', keyword: trimmed.toLowerCase() };
}
// Handle letter-spacing keywords
const letterSpacingKeyword = getValidKeyword(trimmed, LETTER_SPACING_KEYWORDS);
if (letterSpacingKeyword) {
return { type: 'keyword', keyword: letterSpacingKeyword };
}
// Length values (can be negative for letter-spacing)
// Note: letter-spacing doesn't support percentages per CSS spec
const lengthResult = parseLength(trimmed);
if (lengthResult) {
// Reject percentage values - letter-spacing doesn't support them
if ('unit' in lengthResult && lengthResult.unit === '%') {
return null;
}
// Reject calc expressions that contain percentages
if ('expression' in lengthResult && lengthResult.expression.includes('%')) {
return null;
}
return lengthResult;
}
return null;
}
/**
* Convert LetterSpacingValue back to CSS string
*/
export function toCSSValue(parsed) {
if (!parsed) {
return null;
}
// Handle CSS variables
if ('CSSvariable' in parsed) {
return cssVariableToCSSValue(parsed);
}
if ('keyword' in parsed) {
return parsed.keyword;
}
// Handle length values
if ('unit' in parsed && parsed.type === 'length') {
return lengthToCSSValue(parsed);
}
// Handle function expressions (calc, etc.)
if ('expression' in parsed && parsed.type === 'function') {
return `${parsed.function}(${parsed.expression})`;
}
return null;
}