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feat(ix): mark unsupported CSS choice
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,83 @@ | ||
| /** | ||
| * Checks if the CSS code is supported by the current browser. | ||
| * | ||
| * @param {string} code | ||
| */ | ||
| export function isCSSSupported(code) { | ||
| // http://regexr.com/3fvik | ||
| const cssCommentsMatch = /(\/\*)[\s\S]+(\*\/)/g; | ||
| const element = document.createElement("div"); | ||
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| // strip out any CSS comments before applying the code | ||
| code = code.replace(cssCommentsMatch, ""); | ||
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| const vendorPrefixMatch = /^-(?:webkit|moz|ms|o)-/; | ||
| const style = element.style; | ||
| // Expecting declarations to be separated by ";" | ||
| // Declarations with just white space are ignored | ||
| const declarationsArray = code | ||
| .split(";") | ||
| .map((d) => d.trim()) | ||
| .filter((d) => d.length > 0); | ||
|
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| /** | ||
| * @param {string} declaration | ||
| * @returns {boolean} - true if declaration starts with -webkit-, -moz-, -ms- or -o- | ||
| */ | ||
| function hasVendorPrefix(declaration) { | ||
| return vendorPrefixMatch.test(declaration); | ||
| } | ||
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| /** | ||
| * Looks for property name by cutting off optional vendor prefix at the beginning | ||
| * and then cutting off rest of the declaration, starting from any whitespace or ":" in property name. | ||
| * @param {string} declaration - single css declaration, with not white space at the beginning | ||
| * @returns {string} - property name without vendor prefix. | ||
| */ | ||
| function getPropertyNameNoPrefix(declaration) { | ||
| const prefixMatch = vendorPrefixMatch.exec(declaration); | ||
| const prefix = prefixMatch === null ? "" : prefixMatch[0]; | ||
| const declarationNoPrefix = | ||
| prefix === null ? declaration : declaration.slice(prefix.length); | ||
| // Expecting property name to be over, when any whitespace or ":" is found | ||
| const propertyNameSeparator = /[\s:]/; | ||
| return declarationNoPrefix.split(propertyNameSeparator)[0] ?? ""; | ||
| } | ||
|
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| // Clearing previous state | ||
| style.cssText = ""; | ||
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| // List of found and applied properties with vendor prefix | ||
| const appliedPropertiesWithPrefix = new Set(); | ||
| // List of not applied properties - because of lack of support for its name or value | ||
| const notAppliedProperties = new Set(); | ||
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| for (const declaration of declarationsArray) { | ||
| const previousCSSText = style.cssText; | ||
| // Declarations are added one by one, because browsers sometimes combine multiple declarations into one | ||
| // For example Chrome changes "column-count: auto;column-width: 8rem;" into "columns: 8rem auto;" | ||
| style.cssText += declaration + ";"; // ";" was previous removed while using split method | ||
| // In case property name or value is not supported, browsers skip single declaration, while leaving rest of them intact | ||
| const correctlyApplied = style.cssText !== previousCSSText; | ||
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| const vendorPrefixFound = hasVendorPrefix(declaration); | ||
| const propertyName = getPropertyNameNoPrefix(declaration); | ||
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| if (correctlyApplied && vendorPrefixFound) { | ||
| // We are saving applied properties with prefix, so equivalent property with no prefix doesn't need to be supported | ||
| appliedPropertiesWithPrefix.add(propertyName); | ||
| } else if (!correctlyApplied && !vendorPrefixFound) { | ||
| notAppliedProperties.add(propertyName); | ||
| } | ||
| } | ||
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| if (notAppliedProperties.size !== 0) { | ||
| // If property with vendor prefix is supported, we can ignore the fact that browser doesn't support property with no prefix | ||
| for (const substitute of appliedPropertiesWithPrefix) { | ||
| notAppliedProperties.delete(substitute); | ||
| } | ||
| // If any other declaration is not supported, whole block should be marked as invalid | ||
| if (notAppliedProperties.size !== 0) return false; | ||
| } | ||
| return true; | ||
| } |