distance.js

DocumentJS.distance =function  (s1, s2) {
	    if (s1 == s2) {
	        return 0;
	    }
	    var s1_len = s1.length,
			s2_len = s2.length;
	    if (s1_len === 0) {
	        return s2_len;
	    }
	    if (s2_len === 0) {
	        return s1_len;
	    }
	 
        s1 = s1.split('');
        s2 = s2.split('');
	    
	 
	    var v0 = new Array(s1_len+1),
			v1 = new Array(s1_len+1),
			s1_idx=0, 
			s2_idx=0, 
			cost=0;
	    for (s1_idx=0; s1_idx<s1_len+1; s1_idx++) {
	        v0[s1_idx] = s1_idx;
	    }
	    var char_s1='', 
			char_s2='';
	    for (s2_idx=1; s2_idx<=s2_len; s2_idx++) {
	        v1[0] = s2_idx;
	        char_s2 = s2[s2_idx - 1];
	 
	        for (s1_idx=0; s1_idx<s1_len;s1_idx++) {
	            char_s1 = s1[s1_idx];
	            cost = (char_s1 == char_s2) ? 0 : 1;
	            var m_min = v0[s1_idx+1] + 1;
	            var b = v1[s1_idx] + 1;
	            var c = v0[s1_idx] + cost;
	            if (b < m_min) {
	                m_min = b; }
	            if (c < m_min) {
	                m_min = c; }
	            v1[s1_idx+1] = m_min;
	        }
	        var v_tmp = v0;
	        v0 = v1;
	        v1 = v_tmp;
	    }
	    return v0[s1_len];
}