Function createCache

2.0.3/Sizzle-annotation.js:331–346

* Create key-value caches of limited size * @returns {Function(string, Object)} Returns the Object data after storing it on itself with * property name the (space-suffixed) string and (if the cache is larger than Expr.cacheLength) * deleting the oldest entry

()

	 */

	function createCache() {
		var keys = [];

		function cache(key, value) {
			// Use (key + " ") to avoid collision with native prototype properties (see Issue #157)
			// 为了避免缓存太多，导致内存使用过大，所以这里可以设置cache长度。默认是
			// cacheLength: 50,
			if (keys.push(key += " ") > Expr.cacheLength) {
				// Only keep the most recent entries
				// 超过缓存，那就把缓存的第一个删掉
				delete cache[keys.shift()];
			}
			return (cache[key] = value);
		}
		return cache;
	}

	/**
	 * Mark a function for special use by Sizzle