Add MultiTapCipherEncode.mjs

This is the code to execute the Multi Tap Cipher Encode operation.
It takes a string input and returns the number of taps required separated by a delimiter which can be chosen by the user.
More info - https://en.wikipedia.org/wiki/Multi-tap

src/core/operations/MultiTapCipherEncode.mjs

@@ -0,0 +1,62 @@
+/**
+ * @author Necron3574 [kaustubhbm3574@gmail.com]
+ * @copyright Crown Copyright 2021
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+import Utils from "../Utils.mjs";
+import OperationError from "../errors/OperationError.mjs";
+/**
+ * Multi Tap Cipher Encode operation
+ */
+class MultiTapCipherEncode extends Operation {
+
+    /**
+     * MultiTapCipherEncode constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Multi Tap Cipher Encode";
+        this.module = "Default";
+        this.description = "It is a simple substitution cipher which substitutes the alphabets to their corresponding taps on a mobile phone.<br><br>e.g. <code>adg</code> becomes <code>2-3-4</code>";
+        this.infoURL = "https://wikipedia.org/wiki/Multi-tap";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [
+            {
+                name: "Delimiter",
+                type: "option",
+                value: ["Hyphen","Space", "Comma", "Semi-colon", "Colon", "Line feed"]
+            }
+        ];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+      const delim = Utils.charRep(args[0] || "Hyphen");
+      var emap = {"A" :"2","B":"22","C":"222","D":"3","E":"33","F":"333","G":"4","H":"44","I":"444","J":"5","K":"55","L":"555","M":"6","N":"66","O":"666","P":"7","Q":"77","R":"777","S":"7777","T":"8","U":"88","V":"888","W":"9","X":"99","Y":"999","Z":"9999"," ":" "};
+      input = input.toUpperCase();
+      var plaintext = "";
+      for(let i= 0;i<input.length;i++){
+          if(input.charAt(i) != ' ')
+              plaintext += input.charAt(i);
+      }
+      var ciphertext = "";
+      for(let i=0;i<plaintext.length;++i){
+          if(emap[plaintext.charAt(i)] == undefined)
+            throw new OperationError("The input must be only alphabets");
+          ciphertext += emap[plaintext.charAt(i)];
+          if(i!=plaintext.length)
+              ciphertext += delim;
+      }
+      return ciphertext.substring(0,ciphertext.length-1);
+    }
+}
+
+export default MultiTapCipherEncode;