@wix/css-property-parser/dist/evaluators/percentage.js

A comprehensive TypeScript library for parsing and serializing CSS property values with full MDN specification compliance

// Percentage data type parser
// Handles parsing of CSS percentage values according to MDN specification
// https://developer.mozilla.org/en-US/docs/Web/CSS/percentage
import { parse as parseNumber } from './number.js';
import { parse as parseCSSVariable, toCSSValue as cssVariableToCSSValue } from './css-variable.js';
import { isCssVariable } from '../utils/shared-utils.js';
import { parseCSSFunction, cssFunctionToCSSValue } from '../utils/css-function-parser.js';
// Percentage pattern - number followed by %
const PERCENTAGE_REGEX = /^(-?(?:\d+\.?\d*|\.\d+)(?:[eE][+-]?\d+)?)%$/i;
/**
 * Parses a CSS percentage value into structured components
 * @param value - The CSS percentage value string
 * @returns Parsed percentage object or null if invalid
 */
export function parse(value) {
    if (!value || typeof value !== 'string') {
        return null;
    }
    const trimmed = value.trim();
    if (trimmed === '')
        return null;
    // CSS variables - ALWAYS CHECK FIRST
    if (isCssVariable(trimmed)) {
        return parseCSSVariable(trimmed);
    }
    // Handle CSS math functions: calc(), clamp(), min(), max()
    const functionResult = parseCSSFunction(trimmed);
    if (functionResult) {
        return functionResult;
    }
    // Match percentage pattern
    const match = trimmed.match(PERCENTAGE_REGEX);
    if (!match) {
        return null;
    }
    const [, valueStr] = match;
    const numberValue = parseNumber(valueStr);
    if (!numberValue) {
        return null;
    }
    // Check if it's a simple number value (not calc expression or keyword)
    if (!('value' in numberValue)) {
        return null;
    }
    return {
        type: 'percentage',
        value: numberValue.value,
        unit: '%'
    };
}
/**
 * Converts a parsed percentage back to a CSS value string
 * @param parsed - The parsed percentage object
 * @returns CSS value string or null if invalid
 */
export function toCSSValue(parsed) {
    if (!parsed) {
        return null;
    }
    // Handle CSS variables
    if ('CSSvariable' in parsed) {
        return cssVariableToCSSValue(parsed);
    }
    // Handle CSS math function expressions
    if ('expression' in parsed) {
        return cssFunctionToCSSValue(parsed);
    }
    // Handle regular percentage values
    if ('value' in parsed && 'unit' in parsed) {
        return `${parsed.value}${parsed.unit}`;
    }
    return null;
}