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Levenshtein for Javascript

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Calculates the levenshtein distance between two strings

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  1. function levenshtein (s1, s2) {
  2.     // Calculate Levenshtein distance between two strings  
  3.     // 
  4.     // version: 1109.2015
  5.     // discuss at: http://phpjs.org/functions/levenshtein    // +            original by: Carlos R. L. Rodrigues (http://www.jsfromhell.com)
  6.     // +            bugfixed by: Onno Marsman
  7.     // +             revised by: Andrea Giammarchi (http://webreflection.blogspot.com)
  8.     // + reimplemented by: Brett Zamir (http://brett-zamir.me)
  9.     // + reimplemented by: Alexander M Beedie    // *                example 1: levenshtein('Kevin van Zonneveld', 'Kevin van Sommeveld');
  10.     // *                returns 1: 3
  11.     if (s1 == s2) {
  12.         return 0;
  13.     } 
  14.     var s1_len = s1.length;
  15.     var s2_len = s2.length;
  16.     if (s1_len === 0) {
  17.         return s2_len;
  18.     }
  19.     if (s2_len === 0) {
  20.         return s1_len;
  21.     }
  22.      // BEGIN STATIC
  23.     var split = false;
  24.     try {
  25.         split = !('0')[0];
  26.     } catch (e) {
  27.          split = true; // Earlier IE may not support access by string index
  28.     }
  29.     // END STATIC
  30.     if (split) {
  31.         s1 = s1.split('');
  32.         s2 = s2.split('');
  33.     }
  34.  
  35.     var v0 = new Array(s1_len + 1);
  36.     var v1 = new Array(s1_len + 1); 
  37.     var s1_idx = 0,
  38.         s2_idx = 0,
  39.         cost = 0;
  40.     for (s1_idx = 0; s1_idx < s1_len + 1; s1_idx++) {        
  41.          v0[s1_idx] = s1_idx;
  42.     }
  43.     var char_s1 = '',
  44.         char_s2 = '';
  45.     for (s2_idx = 1; s2_idx <= s2_len; s2_idx++) {        
  46.          v1[0] = s2_idx;
  47.         char_s2 = s2[s2_idx - 1];
  48.  
  49.         for (s1_idx = 0; s1_idx < s1_len; s1_idx++) {
  50.             char_s1 = s1[s1_idx];            
  51.             cost = (char_s1 == char_s2) ? 0 : 1;
  52.             var m_min = v0[s1_idx + 1] + 1;
  53.             var b = v1[s1_idx] + 1;
  54.             var c = v0[s1_idx] + cost;
  55.             if (b < m_min) {                
  56.                m_min = b;
  57.             }
  58.             if (c < m_min) {
  59.                 m_min = c;
  60.             }            
  61.             v1[s1_idx + 1] = m_min;
  62.         }
  63.         var v_tmp = v0;
  64.         v0 = v1;
  65.         v1 = v_tmp;    
  66.     }
  67.     return v0[s1_len];
  68. }

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