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Timed in-memory storage in JavaScript
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| /** | |
| The MIT License (MIT) | |
| Copyright (c) 2013 Matt Anderson (Question Everything, LLC) | |
| Permission is hereby granted, free of charge, to any person obtaining a copy | |
| of this software and associated documentation files (the "Software"), to deal | |
| in the Software without restriction, including without limitation the rights | |
| to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
| copies of the Software, and to permit persons to whom the Software is | |
| furnished to do so, subject to the following conditions: | |
| The above copyright notice and this permission notice shall be included in | |
| all copies or substantial portions of the Software. | |
| THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
| IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
| FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
| AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
| LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
| OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN | |
| THE SOFTWARE. | |
| */ | |
| /** | |
| Create a CacheMap instance with a provided timeout value for any values | |
| placed within the map. | |
| A CacheMap created without a timeoutValue parameter will never time out | |
| the value set unless a uniqueTimeout is passed. | |
| */ | |
| var CacheMap = function(timeOutValue) { | |
| this.constructor(timeOutValue); | |
| }; | |
| /** | |
| Assign the timeout and create objects to store cached content | |
| and timeout ids. | |
| */ | |
| CacheMap.prototype.constructor = function(timeOutValue) { | |
| this.timeOutValue = timeOutValue; | |
| this.timeoutMap = {}; | |
| this.storageMap = {}; | |
| }; | |
| /** | |
| Set content in the CacheMap. If there is a pending timeout associated | |
| with the provided key, it will be clearned, a new value set, and a | |
| new timeout created. | |
| If the uniqueTimeout parameter is passed, it will be used to timeout | |
| the stored value rather than the default timeout value provided in the | |
| constructor. | |
| */ | |
| CacheMap.prototype.set = function(key, value, uniqueTimeout) { | |
| // check for timeout associated with key | |
| if(this.timeoutMap[key]) | |
| clearTimeout(this.timeoutMap[key]); | |
| // set value in local storage | |
| this.storageMap[key] = value; | |
| // here we check to see if: the global timeout is defined (and that it is not -1) | |
| // or that we have a uniqueTimeout passed and that it is not -1. | |
| if((this.timeOutValue && this.timeOutValue != -1) || // we have a global timeout | |
| (uniqueTimeout && uniqueTimeout != -1)) { // OR we have a unique timeout | |
| // set timeout & association | |
| this.timeoutMap[key] = | |
| setTimeout((function(key){ | |
| return function() { | |
| delete this.timeoutMap[key]; | |
| delete this.storageMap[key]; | |
| }.bind(this); | |
| }.bind(this))(key), uniqueTimeout || this.timeOutValue); | |
| } | |
| }; | |
| /** | |
| Attempts to retrieve a value from the internal storage object. | |
| If no value is present, undefined is returned, otherwise the | |
| stored value will be returned. | |
| */ | |
| CacheMap.prototype.get = function(key) { | |
| return this.storageMap[key]; | |
| }; |
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| var testObject = new CacheMap(); // create new cachemap with no global timeout | |
| testObject.set("testKey1", "1"); // this value will never time out | |
| testObject.set("testKey2", "2", 1500); // this will timeout in 1.5 seconds | |
| testObject.set("testKey3", "3", 3000); // this will timeout in 3.0 seconds | |
| setInterval(function(){ | |
| console.log("Test Key 1:", testObject.get("testKey1")); | |
| console.log("Test Key 2:", testObject.get("testKey2")); | |
| console.log("Test Key 3:", testObject.get("testKey3")); | |
| }, 500); | |
| /* | |
| Example Output: | |
| Test Key 1: 1 | |
| Test Key 2: 2 | |
| Test Key 3: 3 | |
| Test Key 1: 1 | |
| Test Key 2: 2 | |
| Test Key 3: 3 | |
| Test Key 1: 1 | |
| Test Key 2: undefined | |
| Test Key 3: 3 | |
| Test Key 1: 1 | |
| Test Key 2: undefined | |
| Test Key 3: 3 | |
| Test Key 1: 1 | |
| Test Key 2: undefined | |
| Test Key 3: 3 | |
| Test Key 1: 1 | |
| Test Key 2: undefined | |
| Test Key 3: undefined | |
| */ |
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