Nodejs String Soundex soundex( )

Method Source Code

/**//from www .j  a  v  a2  s  . co  m
 * @return {String} The soundex code for the String item's value.
 */
String.prototype.soundex = function( ){

   var i, j, r;
   
   var keyLength = 4; // key size
   
   // mapping of letters to soundex codes
   var map = { B:1,F:1,P:1,V:1,C:2,G:2,J:2,K:2,Q:2,S:2,X:2,Z:2,D:3,T:3,L:4,M:5,N:5,R:6 };
   
   // assign first character to array 'r', the rest to array 's'
   var r = (s = this.toUpperCase().replace(/[^A-Z]/g, "").split("")).splice(0, 1);

   // object to determine the soundex code - if Array.protype.reduc was available it would be neater than this 
   var key = {
       items : [],
      // private - adds the soundex code for the given letter
       _check: function(e) {
         var m = map[e]; // lookup the mapping value
         var l = this.items.length - 1; // last but one item
         if ( m ){ // some letters don't have mappings, so undefined
            if ( this.items[l] != m ){
                    this.items.push(m); // add the mapping code to the key's item
               return true;
               }
         }
       },
      // add, unshift, toString are interface methods to items[] & _check 
       add:  function(e) { //
           this._check(e);
       },
       unshift: function(e) { //
           this.items.unshift(e);
       },
       toString: function(e) { // output
           return this.items.join("");
       }
   };

   var result = s.forEach(key.add, key); // generate key
   key.unshift(r); // prepend the first character of the string

   // return the stringed version of the key, suffix with zeroes when it is shorter
   if ( keyLength > key.toString().length ){
      return key.toString() + (new Array(keyLength - key.toString().length + 1)).join("0");
   }
   else{
      return key.toString().substring(0,keyLength); // truncate to 4 characters
   }
}

Related

1. soundex()

   String.prototype.soundex = function()
     return this.charAt(0).toUpperCase() + this.slice(1).toLowerCase()
       .replace(/\w/g, function($0)
         return String.prototype.soundex.table[$0];
       })
       .replace(/(.)\1+/g, '$1')
       .slice(0, 3)
   ...
   

2. soundex(p)

   String.prototype.soundex = function(p){
     var i, j, l, r, p = isNaN(p) ? 4 : p > 10 ? 10 : p < 4 ? 4 : p,
     m = {BFPV: 1, CGJKQSXZ: 2, DT: 3, L: 4, MN: 5, R: 6},
     r = (s = this.toUpperCase().replace(/[^A-Z]/g, "").split("")).splice(0, 1);
     for(i = -1, l = s.length; ++i < l;)
       for(j in m)
         if(j.indexOf(s[i]) + 1 && r[r.length-1] != m[j] && r.push(m[j]))
           break;
     return r.length > p && (r.length = p), r.join("") + (new Array(p - r.length + 1)).join("0");
   ...
   

3. soundex(p)

   String.prototype.soundex = function(p){ 
       var i, j, r, p = isNaN(p) ? 4 : p > 10 ? 10 : p < 4 ? 4 : p,
       m = {BFPV: 1, CGJKQSXZ: 2, DT: 3, L: 4, MN: 5, R: 6},
       r = (s = this.toUpperCase().replace(/[^A-Z]/g, "").split("")).splice(0, 1);
       for(i in s)
           for(j in m)
               if(j.indexOf(s[i]) + 1 && r[r.length-1] != m[j] && r.push(m[j]))
                   break;
       return r.length > p && (r.length = p), r.join("") + (new Array(p - r.length + 1)).join("0");
   ...
   

4. soundex.init(table)

   String.prototype.soundex.init = function(table)
     String.prototype.soundex.table = {};
     table = table || {
       'bfpv': '1', 
       'cgjkqsxz': '2', 
       'dt': '3', 
       'l': '4', 
       'mn': '5', 
   ...