Soundex is a phonetic algorithm for indexing names by sound, as pronounced in English. - Node.js String

Node.js examples for String:Algorithm

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Description

Soundex is a phonetic algorithm for indexing names by sound, as pronounced in English.

Demo Code

/**/*from www . j  av  a  2s.c om*/
 * 19 May 2008
 * Soundex is a phonetic algorithm for indexing names by sound, as pronounced in English.
 *
 * @author Matt Chadburn <matt@commuterjoy.co.uk>
 */

/**
 * @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.reduce 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
  }
}

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