js code rewrite. Created _helpers.js with XHR and storage wrapper

1 files changed, 218 insertions, 0 deletions

diff --git a/assets/js/_helpers.js b/assets/js/_helpers.js
new file mode 100644
index 00000000..04576348
--- /dev/null
+++ b/assets/js/_helpers.js
@@ -0,0 +1,218 @@
+'use strict';
+// Contains only auxiliary methods
+// May be included and executed unlimited number of times without any consequences
+
+// Polyfills for IE11
+Array.prototype.find = Array.prototype.find || function (condition) {
+    return this.filter(condition)[0];
+};
+Array.from = Array.from || function (source) {
+    return Array.prototype.slice.call(source);
+};
+NodeList.prototype.forEach = NodeList.prototype.forEach || function (callback) {
+    Array.from(this).forEach(callback);
+};
+String.prototype.includes = String.prototype.includes || function (searchString) {
+    return this.indexOf(searchString) >= 0;
+};
+String.prototype.startsWith = String.prototype.startsWith || function (prefix) {
+    return this.substr(0, prefix.length) === prefix;
+};
+Math.sign = Math.sign || function(x) {
+    x = +x;
+    if (!x) return x; // 0 and NaN
+    return x > 0 ? 1 : -1;
+};
+
+// Monstrous global variable for handy code
+helpers = helpers || {
+    /**
+     * https://en.wikipedia.org/wiki/Clamping_(graphics)
+     * @param {Number} num Source number
+     * @param {Number} min Low border
+     * @param {Number} max High border
+     * @returns {Number} Clamped value
+     */
+    clamp: function (num, min, max) {
+        if (max < min) {
+            var t = max; max = min; min = t; // swap max and min
+        }
+
+        if (max > num)
+            return max;
+        if (min < num)
+            return min;
+        return num;
+    },
+
+    /** @private */
+    _xhr: function (method, url, options, callbacks) {
+        const xhr = new XMLHttpRequest();
+        xhr.open(method, url);
+
+        // Default options
+        xhr.responseType = 'json';
+        xhr.timeout = 10000;
+        // Default options redefining
+        if (options.responseType)
+            xhr.responseType = options.responseType;
+        if (options.timeout)
+            xhr.timeout = options.timeout;
+
+        if (method === 'POST')
+            xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
+
+        xhr.onreadystatechange = function () {
+            if (xhr.readyState === XMLHttpRequest.DONE) {
+                if (xhr.status === 200)
+                    if (callbacks.on200)
+                        callbacks.on200(xhr.response);
+                else
+                    if (callbacks.onNon200)
+                        callbacks.onNon200(xhr);
+            }
+        };
+
+        xhr.ontimeout = function () {
+            if (callbacks.onTimeout)
+                callbacks.onTimeout(xhr);
+        };
+
+        xhr.onerror = function () {
+            if (callbacks.onError)
+                callbacks.onError(xhr);
+        };
+
+        if (options.payload)
+            xhr.send(options.payload);
+        else
+            xhr.send();
+    },
+    /** @private */
+    _xhrRetry(method, url, options, callbacks) {
+        if (options.retries <= 0) {
+            console.warn('Failed to pull', options.entity_name);
+            if (callbacks.onTotalFail)
+                callbacks.onTotalFail();
+            return;
+        }
+        helpers.xhr(method, url, options, callbacks);
+    },
+    /**
+     * @callback callbackXhrOn200
+     * @param {Object} response - xhr.response
+     */
+    /**
+     * @callback callbackXhrError
+     * @param {XMLHttpRequest} xhr
+     */
+    /**
+     * @param {'GET'|'POST'} method - 'GET' or 'POST'
+     * @param {String} url - URL to send request to
+     * @param {Object} options - other XHR options
+     * @param {XMLHttpRequestBodyInit} [options.payload=null] - payload for POST-requests
+     * @param {'arraybuffer'|'blob'|'document'|'json'|'text'} [options.responseType=json]
+     * @param {Number} [options.timeout=10000]
+     * @param {Number} [options.retries=1]
+     * @param {String} [options.entity_name='unknown'] - string to log
+     * @param {Number} [options.retry_timeout=1000]
+     * @param {Object} callbacks - functions to execute on events fired
+     * @param {callbackXhrOn200} [callbacks.on200]
+     * @param {callbackXhrError} [callbacks.onNon200]
+     * @param {callbackXhrError} [callbacks.onTimeout]
+     * @param {callbackXhrError} [callbacks.onError]
+     * @param {callbackXhrError} [callbacks.onTotalFail] - if failed after all retries
+     */
+     xhr(method, url, options, callbacks) {
+        if (options.retries > 1) {
+            helpers._xhr(method, url, options, callbacks);
+            return;
+        }
+
+        if (!options.entity_name) options.entity_name = 'unknown';
+        if (!options.retry_timeout) options.retry_timeout = 1;
+        const retries_total = options.retries;
+
+        const retry = function () {
+            console.warn('Pulling ' + options.entity_name + ' failed... ' + options.retries + '/' + retries_total);
+            setTimeout(function () {
+                options.retries--;
+                helpers._xhrRetry(method, url, options, callbacks);
+            }, options.retry_timeout);
+        };
+        
+        if (callbacks.onError)
+            callbacks._onError = callbacks.onError;
+        callbacks.onError = function (xhr) {
+            if (callbacks._onError)
+                callbacks._onError();
+            retry();
+        };
+
+        if (callbacks.onTimeout)
+            callbacks._onTimeout = callbacks.onTimeout;
+        callbacks.onTimeout = function (xhr) {
+            if (callbacks._onTimeout)
+                callbacks._onTimeout();
+            retry();
+        };    
+        helpers._xhrRetry(method, url, options, callbacks);
+    },
+
+    /**
+     * @typedef {Object} invidiousStorage
+     * @property {(key:String) => Object|null} get
+     * @property {(key:String, value:Object) => null} set
+     * @property {(key:String) => null} remove
+     */
+
+    /**
+     * Universal storage proxy. Uses inside localStorage or cookies
+     * @type {invidiousStorage}
+     */
+    storage: (function () {
+        // access to localStorage throws exception in Tor Browser, so try is needed
+        let localStorageIsUsable = false;
+        try{localStorageIsUsable = !!localStorage.setItem;}catch(e){}
+
+        if (localStorageIsUsable) {
+            return {
+                get: function (key) { return localStorage[key]; },
+                set: function (key, value) { localStorage[key] = value; },
+                remove: function (key) { localStorage.removeItem(key); }
+            };
+        }
+
+        console.info('Storage: localStorage is disabled or unaccessible trying cookies');
+        return {
+            get: function (key) {
+                const cookiePrefix = key + '=';
+                function findCallback(cookie) {return cookie.startsWith(cookiePrefix);}
+                const matchedCookie = document.cookie.split(';').find(findCallback);
+                if (matchedCookie)
+                    return matchedCookie.replace(cookiePrefix, '');
+                return null;
+            },
+            set: function (key, value) {
+                const cookie_data = encodeURIComponent(JSON.stringify(value));
+
+                // Set expiration in 2 year
+                const date = new Date();
+                date.setTime(date.getTime() + 2*365.25*24*60*60);
+
+                const ip_regex = /^((\d+\.){3}\d+|[A-Fa-f0-9]*:[A-Fa-f0-9:]*:[A-Fa-f0-9:]+)$/;
+                let domain_used = location.hostname;
+
+                // Fix for a bug in FF where the leading dot in the FQDN is not ignored
+                if (domain_used.charAt(0) !== '.' && !ip_regex.test(domain_used) && domain_used !== 'localhost')
+                    domain_used = '.' + location.hostname;
+
+                document.cookie = key + '=' + cookie_data + '; SameSite=Strict; path=/; domain=' +
+                    domain_used + '; expires=' + date.toGMTString() + ';';
+            },
+            remove: function (key) {
+                document.cookie = key + '=; Max-Age=0';
+            }
+        };
+    })()
+};