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authorFlorian Dold <florian.dold@gmail.com>2017-05-03 15:35:00 +0200
committerFlorian Dold <florian.dold@gmail.com>2017-05-03 15:35:00 +0200
commitde98e0b232509d5f40c135d540a70e415272ff85 (patch)
treea79222a5b58484ab3b80d18efcaaa7ccc4769b33 /node_modules/nth-check/parse.js
parente0c9d480a73fa629c1e4a47d3e721f1d2d345406 (diff)
node_modules
Diffstat (limited to 'node_modules/nth-check/parse.js')
-rw-r--r--node_modules/nth-check/parse.js40
1 files changed, 40 insertions, 0 deletions
diff --git a/node_modules/nth-check/parse.js b/node_modules/nth-check/parse.js
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+++ b/node_modules/nth-check/parse.js
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+module.exports = parse;
+
+//following http://www.w3.org/TR/css3-selectors/#nth-child-pseudo
+
+//[ ['-'|'+']? INTEGER? {N} [ S* ['-'|'+'] S* INTEGER ]?
+var re_nthElement = /^([+\-]?\d*n)?\s*(?:([+\-]?)\s*(\d+))?$/;
+
+/*
+ parses a nth-check formula, returns an array of two numbers
+*/
+function parse(formula){
+ formula = formula.trim().toLowerCase();
+
+ if(formula === "even"){
+ return [2, 0];
+ } else if(formula === "odd"){
+ return [2, 1];
+ } else {
+ var parsed = formula.match(re_nthElement);
+
+ if(!parsed){
+ throw new SyntaxError("n-th rule couldn't be parsed ('" + formula + "')");
+ }
+
+ var a;
+
+ if(parsed[1]){
+ a = parseInt(parsed[1], 10);
+ if(isNaN(a)){
+ if(parsed[1].charAt(0) === "-") a = -1;
+ else a = 1;
+ }
+ } else a = 0;
+
+ return [
+ a,
+ parsed[3] ? parseInt((parsed[2] || "") + parsed[3], 10) : 0
+ ];
+ }
+}