forked from lix-project/lix-website
222 lines
7.1 KiB
JavaScript
222 lines
7.1 KiB
JavaScript
// Calculate the specificity for a selector by dividing it into simple selectors and counting them
|
|
var calculate = function(input) {
|
|
var selectors,
|
|
selector,
|
|
i,
|
|
len,
|
|
results = [];
|
|
|
|
// Separate input by commas
|
|
selectors = input.split(',');
|
|
|
|
for (i = 0, len = selectors.length; i < len; i += 1) {
|
|
selector = selectors[i];
|
|
if (selector.length > 0) {
|
|
results.push(calculateSingle(selector));
|
|
}
|
|
}
|
|
|
|
return results;
|
|
};
|
|
|
|
/**
|
|
* Calculates the specificity of CSS selectors
|
|
* http://www.w3.org/TR/css3-selectors/#specificity
|
|
*
|
|
* Returns an object with the following properties:
|
|
* - selector: the input
|
|
* - specificity: e.g. 0,1,0,0
|
|
* - parts: array with details about each part of the selector that counts towards the specificity
|
|
* - specificityArray: e.g. [0, 1, 0, 0]
|
|
*/
|
|
var calculateSingle = function(input) {
|
|
var selector = input,
|
|
findMatch,
|
|
typeCount = {
|
|
'a': 0,
|
|
'b': 0,
|
|
'c': 0
|
|
},
|
|
parts = [],
|
|
// The following regular expressions assume that selectors matching the preceding regular expressions have been removed
|
|
attributeRegex = /(\[[^\]]+\])/g,
|
|
idRegex = /(#[^\#\s\+>~\.\[:\)]+)/g,
|
|
classRegex = /(\.[^\s\+>~\.\[:\)]+)/g,
|
|
pseudoElementRegex = /(::[^\s\+>~\.\[:]+|:first-line|:first-letter|:before|:after)/gi,
|
|
// A regex for pseudo classes with brackets - :nth-child(), :nth-last-child(), :nth-of-type(), :nth-last-type(), :lang()
|
|
// The negation psuedo class (:not) is filtered out because specificity is calculated on its argument
|
|
// :global and :local are filtered out - they look like psuedo classes but are an identifier for CSS Modules
|
|
pseudoClassWithBracketsRegex = /(:(?!not|global|local)[\w-]+\([^\)]*\))/gi,
|
|
// A regex for other pseudo classes, which don't have brackets
|
|
pseudoClassRegex = /(:(?!not|global|local)[^\s\+>~\.\[:]+)/g,
|
|
elementRegex = /([^\s\+>~\.\[:]+)/g;
|
|
|
|
// Find matches for a regular expression in a string and push their details to parts
|
|
// Type is "a" for IDs, "b" for classes, attributes and pseudo-classes and "c" for elements and pseudo-elements
|
|
findMatch = function(regex, type) {
|
|
var matches, i, len, match, index, length;
|
|
if (regex.test(selector)) {
|
|
matches = selector.match(regex);
|
|
for (i = 0, len = matches.length; i < len; i += 1) {
|
|
typeCount[type] += 1;
|
|
match = matches[i];
|
|
index = selector.indexOf(match);
|
|
length = match.length;
|
|
parts.push({
|
|
selector: input.substr(index, length),
|
|
type: type,
|
|
index: index,
|
|
length: length
|
|
});
|
|
// Replace this simple selector with whitespace so it won't be counted in further simple selectors
|
|
selector = selector.replace(match, Array(length + 1).join(' '));
|
|
}
|
|
}
|
|
};
|
|
|
|
// Replace escaped characters with plain text, using the "A" character
|
|
// https://www.w3.org/TR/CSS21/syndata.html#characters
|
|
(function() {
|
|
var replaceWithPlainText = function(regex) {
|
|
var matches, i, len, match;
|
|
if (regex.test(selector)) {
|
|
matches = selector.match(regex);
|
|
for (i = 0, len = matches.length; i < len; i += 1) {
|
|
match = matches[i];
|
|
selector = selector.replace(match, Array(match.length + 1).join('A'));
|
|
}
|
|
}
|
|
},
|
|
// Matches a backslash followed by six hexadecimal digits followed by an optional single whitespace character
|
|
escapeHexadecimalRegex = /\\[0-9A-Fa-f]{6}\s?/g,
|
|
// Matches a backslash followed by fewer than six hexadecimal digits followed by a mandatory single whitespace character
|
|
escapeHexadecimalRegex2 = /\\[0-9A-Fa-f]{1,5}\s/g,
|
|
// Matches a backslash followed by any character
|
|
escapeSpecialCharacter = /\\./g;
|
|
|
|
replaceWithPlainText(escapeHexadecimalRegex);
|
|
replaceWithPlainText(escapeHexadecimalRegex2);
|
|
replaceWithPlainText(escapeSpecialCharacter);
|
|
}());
|
|
|
|
// Remove anything after a left brace in case a user has pasted in a rule, not just a selector
|
|
(function() {
|
|
var regex = /{[^]*/gm,
|
|
matches, i, len, match;
|
|
if (regex.test(selector)) {
|
|
matches = selector.match(regex);
|
|
for (i = 0, len = matches.length; i < len; i += 1) {
|
|
match = matches[i];
|
|
selector = selector.replace(match, Array(match.length + 1).join(' '));
|
|
}
|
|
}
|
|
}());
|
|
|
|
// Add attribute selectors to parts collection (type b)
|
|
findMatch(attributeRegex, 'b');
|
|
|
|
// Add ID selectors to parts collection (type a)
|
|
findMatch(idRegex, 'a');
|
|
|
|
// Add class selectors to parts collection (type b)
|
|
findMatch(classRegex, 'b');
|
|
|
|
// Add pseudo-element selectors to parts collection (type c)
|
|
findMatch(pseudoElementRegex, 'c');
|
|
|
|
// Add pseudo-class selectors to parts collection (type b)
|
|
findMatch(pseudoClassWithBracketsRegex, 'b');
|
|
findMatch(pseudoClassRegex, 'b');
|
|
|
|
// Remove universal selector and separator characters
|
|
selector = selector.replace(/[\*\s\+>~]/g, ' ');
|
|
|
|
// Remove any stray dots or hashes which aren't attached to words
|
|
// These may be present if the user is live-editing this selector
|
|
selector = selector.replace(/[#\.]/g, ' ');
|
|
|
|
// Remove the negation psuedo-class (:not) but leave its argument because specificity is calculated on its argument
|
|
// Remove non-standard :local and :global CSS Module identifiers because they do not effect the specificity
|
|
selector = selector.replace(/:not/g, ' ');
|
|
selector = selector.replace(/:local/g, ' ');
|
|
selector = selector.replace(/:global/g, ' ');
|
|
selector = selector.replace(/[\(\)]/g, ' ');
|
|
|
|
// The only things left should be element selectors (type c)
|
|
findMatch(elementRegex, 'c');
|
|
|
|
// Order the parts in the order they appear in the original selector
|
|
// This is neater for external apps to deal with
|
|
parts.sort(function(a, b) {
|
|
return a.index - b.index;
|
|
});
|
|
|
|
return {
|
|
selector: input,
|
|
specificity: '0,' + typeCount.a.toString() + ',' + typeCount.b.toString() + ',' + typeCount.c.toString(),
|
|
specificityArray: [0, typeCount.a, typeCount.b, typeCount.c],
|
|
parts: parts
|
|
};
|
|
};
|
|
|
|
/**
|
|
* Compares two CSS selectors for specificity
|
|
* Alternatively you can replace one of the CSS selectors with a specificity array
|
|
*
|
|
* - it returns -1 if a has a lower specificity than b
|
|
* - it returns 1 if a has a higher specificity than b
|
|
* - it returns 0 if a has the same specificity than b
|
|
*/
|
|
var compare = function(a, b) {
|
|
var aSpecificity,
|
|
bSpecificity,
|
|
i;
|
|
|
|
if (typeof a ==='string') {
|
|
if (a.indexOf(',') !== -1) {
|
|
throw 'Invalid CSS selector';
|
|
} else {
|
|
aSpecificity = calculateSingle(a)['specificityArray'];
|
|
}
|
|
} else if (Array.isArray(a)) {
|
|
if (a.filter(function(e) { return (typeof e === 'number'); }).length !== 4) {
|
|
throw 'Invalid specificity array';
|
|
} else {
|
|
aSpecificity = a;
|
|
}
|
|
} else {
|
|
throw 'Invalid CSS selector or specificity array';
|
|
}
|
|
|
|
if (typeof b ==='string') {
|
|
if (b.indexOf(',') !== -1) {
|
|
throw 'Invalid CSS selector';
|
|
} else {
|
|
bSpecificity = calculateSingle(b)['specificityArray'];
|
|
}
|
|
} else if (Array.isArray(b)) {
|
|
if (b.filter(function(e) { return (typeof e === 'number'); }).length !== 4) {
|
|
throw 'Invalid specificity array';
|
|
} else {
|
|
bSpecificity = b;
|
|
}
|
|
} else {
|
|
throw 'Invalid CSS selector or specificity array';
|
|
}
|
|
|
|
for (i = 0; i < 4; i += 1) {
|
|
if (aSpecificity[i] < bSpecificity[i]) {
|
|
return -1;
|
|
} else if (aSpecificity[i] > bSpecificity[i]) {
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
};
|
|
|
|
export {
|
|
calculate,
|
|
compare
|
|
};
|