Improved rates caching

index.js

@@ -159,7 +159,9 @@ class CurrencyConverter {
         this.currencyTo = ""
         this.currencyAmount = 1
         this.convertedValue = 0
-        this.isDecimalComma = false
+        this.isDecimalComma = false;
+        this.isRatesCaching = false;
+        this.ratesCacheDuration = 0;
         this.ratesCache = {};
 
         if(params != undefined){
@@ -228,13 +230,41 @@ class CurrencyConverter {
         return text_
     }
 
+    setupRatesCache(ratesCacheOptions) {
+        if (typeof ratesCacheOptions != "object")
+            throw new TypeError("ratesCacheOptions should be an object")
+
+        if (ratesCacheOptions.isRatesCaching === undefined)
+            throw new Error(`ratesCacheOptions should have a property called isRatesCaching`)
+
+        if (typeof ratesCacheOptions.isRatesCaching != "boolean")
+            throw new TypeError("ratesCacheOptions.isRatesCaching should be a boolean")
+
+        if (typeof ratesCacheOptions.ratesCacheDuration != "number")
+            throw new TypeError("ratesCacheOptions.ratesCacheDuration should be a number")
+
+        if(ratesCacheOptions.ratesCacheDuration <= 0)
+            throw new Error("ratesCacheOptions.ratesCacheDuration should be a positive number of seconds")
+
+        this.isRatesCaching = ratesCacheOptions.isRatesCaching;
+
+        if (ratesCacheOptions.ratesCacheDuration === undefined)
+            this.ratesCacheDuration = 3600000; // Defaults to 3600 seconds (1 hour)
+        else
+            this.ratesCacheDuration = ratesCacheOptions.ratesCacheDuration * 1000;
+
+        return this
+    }
+
     rates(){
         if(this.currencyFrom === this.currencyTo)
             return new Promise((resolve, _) => {resolve(this.currencyAmount) })
         else
             let currencyPair = this.currencyFrom.toUpperCase() + this.currencyTo.toUpperCase();
             if (currencyPair in this.ratesCache)
-                return this.ratesCache[currencyPair];
+            return new Promise((resolve, _) => {
+                resolve(this.ratesCache[currencyPair]);
+            });
             else
                 return got(`https://www.google.co.in/search?q=${this.currencyFrom}+to+${this.currencyTo}+&hl=en`)
                     .then((html) => {
@@ -251,8 +281,10 @@ class CurrencyConverter {
                             if(rates.includes(","))
                                 rates = this.replaceAll(rates, ",", "")
                         }
-                        this.ratesCache[currencyPair] = parseFloat(rates);
-                        this.removeCurrencyPairFromRatesCache(currencyPair);
+                        if (this.isRatesCaching) {
+                            this.ratesCache[currencyPair] = parseFloat(rates);
+                            this.removeCurrencyPairFromRatesCache(currencyPair);
+                        }
                         return parseFloat(rates)
                 })
     }
@@ -296,7 +328,7 @@ class CurrencyConverter {
         // Deletes cached currencyPair rate an hour later
         setTimeout(function() {
             delete this.ratesCache[currencyPair];
-        }, 3600000);
+        }, this.ratesCacheDuration);
     }
   }
 

readme.md

@@ -75,6 +75,23 @@ currencyConverter.rates().then((response) => {
 })
 ```
 
+Rates can be cached. To implement rate caching, instantiate an object of CurrencyConverter only once in your project, in a CurrencyConverter file, and setup rates caching then import the instance of CurrencyConverter from the CurrencyConverter file in your project across the rest of your project. Use chaining to convert currencies when caching is implemented. Below is an example of a CurrencyConverter file.
+
+```javascript
+const CC = require('currency-converter-lt')
+
+let currencyConverter = new CC()
+
+let ratesCacheOptions = {
+    isRatesCaching: true, // Set this boolean to true to implement rate caching
+    ratesCacheDuration: 3600 // Set this to a positive number to set the number of seconds you want your rates to be cached. Defaults to 3600 seconds (1 hour)
+}
+
+currencyConverter = currencyConverter.setupRatesCache(ratesCacheOptions)
+
+module.exports = currencyConverter
+```
+
 Chaining is also supported.
 
 ```javascript

test/test.js

@@ -17,7 +17,7 @@ describe("currencyConverter", () =>  {
             let CC_ = new CC()
             assert.equal(CC_.currencyFrom, "")
         })
-    
+
         it("should instantiate an object with json object as a parameter", () =>  {
             let CC_ = new CC({from:"GBP", to:"CAD", amount: 100})
             assert.equal(CC_.currencyFrom, "GBP")
@@ -178,9 +178,45 @@ describe("currencyConverter", () =>  {
             expect(() => currencyConverter.currencyName("DDD")).to.throw(Error);
         })
     })
+
+    describe("setupRatesCache", () =>  {
+        it("should throw a TypeError", () =>  {
+            expect(() => currencyConverter.setupRatesCache(5)).to.throw(TypeError);
+        })
+
+        it("should throw a TypeError", () =>  {
+            let ratesCacheOptions = {
+                isRatesCaching: 3
+            }
+            expect(() => currencyConverter.setupRatesCache(ratesCacheOptions)).to.throw(TypeError);
+        })
+
+        it("should throw a TypeError", () =>  {
+            let ratesCacheOptions = {
+                isRatesCaching: true,
+                ratesCacheDuration: "10"
+            }
+            expect(() => currencyConverter.setupRatesCache(ratesCacheOptions)).to.throw(TypeError);
+        })
+
+        it("should throw an Error", () =>  {
+            let ratesCacheOptions = {
+                ratesCacheDuration: 50
+            }
+            expect(() => currencyConverter.setupRatesCache(ratesCacheOptions)).to.throw(Error);
+        })
+
+        it("should throw an Error", () =>  {
+            let ratesCacheOptions = {
+                isRatesCaching: true,
+                ratesCacheDuration: -50
+            }
+            expect(() => currencyConverter.setupRatesCache(ratesCacheOptions)).to.throw(Error);
+        })
+    })
 })
 
 // console.log(cf)
 
 
-// console.log(c.currencies)
+// console.log(c.currencies)