ARRL 4784

The Care and Feeding of Transmission Lines

• Author:Joel R. Hallas, W1ZR
• ISBN: 0; }, getCacheStorage(cacheKey) { const storage = JSON.parse(hyva.getBrowserStorage().getItem(localStorageNamespace)) || {}; return storage[cacheKey] || null; }, saveCacheStorage(products) { const storage = JSON.parse(hyva.getBrowserStorage().getItem(localStorageNamespace)) || {}; storage[this.getCacheKey()] = { 'product_list': products, 'added_at': new Date().getTime() }; hyva.getBrowserStorage().setItem(localStorageNamespace, JSON.stringify(storage)); }, getProductsFromCache() { const products = this.getCacheStorage(this.getCacheKey()); if (products && this.validateCacheLifetime(products)) { return products.product_list; } return null; }, loadProductsFromServer() { if (this.isLoading) { return; } this.isLoading = true; return fetch(this.ajaxData.url + '?' + this.buildQueryString(this.ajaxData.originalRequest), { 'headers': { 'content-type': 'application/x-www-form-urlencoded; charset=UTF-8', }, 'method': 'GET' }) .then(response => response.json()) .then(data => { if (!data.status) { return; } this.products = Object.values(data.productList); this.saveCacheStorage(data.productList); window.dispatchEvent(new CustomEvent('also-bough-products-loaded')); }) .catch(function (error) { typeof window.dispatchMessages !== 'undefined' && window.dispatchMessages( [{ type: 'error', text: error }], 5000 ); }).finally(() => this.isLoading = false); }, validateCacheLifetime(products) { return new Date().getTime() - products.added_at < this.ajaxData.cache_lifetime * 1000; }, getCacheKey() { const originalRequest = this.ajaxData.originalRequest; return originalRequest.action + '_' + originalRequest.entity_id; }, buildQueryString(params) { const queryStringArray = []; for (const key in params) { if (params.hasOwnProperty(key)) { const value = params[key]; if (Array.isArray(value)) { value.forEach((item, index) => { queryStringArray.push(this.buildQueryString({ [key + '[' + index + ']']: item })); }); } else if (typeof value === 'object' && value !== null) { queryStringArray.push(this.buildQueryString(value)); } else { queryStringArray.push(`${encodeURIComponent(key)}=${encodeURIComponent(value)}`); } } } return queryStringArray.join('&'); } } }

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