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JavaScript - Soundex algorithm implementation

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In this short article, we would like to show how to implement the Soundex algorithm in JavaScript.

Below algorithm calculates Soundex code for indicated string.

Soundex codes can be used to:

• check words similarity (as an alternative: fuzzy comparison with bigrams),
• build fuzzy searching in databases,
• implement fuzzy map data structure (e.g. FuzzyHashMap).

Note: that algorithm works well for English words.

Example implementation:

// ONLINE-RUNNER:browser;

const findStartingCode = word => {
return word[0].toUpperCase();
};

const findLetterCode = letter => {
switch (letter.toUpperCase()) {
case 'B':
case 'F':
case 'P':
case 'V':
return '1';

case 'C':
case 'G':
case 'J':
case 'K':
case 'Q':
case 'S':
case 'X':
case 'Z':
return '2';

case 'D':
case 'T':
return '3';

case 'L':
return '4';

case 'M':
case 'N':
return '5';

case 'R':
return '6';

default:
return null;
}
};

const calculateSoundexCode = word => {
if (word) {
let wordCode = findStartingCode(word);
let lastCode = findLetterCode(wordCode); // wordCode contains one letter at the begining
for (let i = 1; i < word.length; ++i) {
const letterCode = findLetterCode(word[i]);
if (letterCode && letterCode != lastCode) {
wordCode += letterCode;
if (wordCode.length == 4) {
break;
}
}
lastCode = letterCode;
}
for (let i = wordCode.length; i < 4; ++i) {
wordCode += '0';
}
return wordCode;
}
return null;
};

// Usage example:

console.log(calculateSoundexCode('Robert'));    // R163
console.log(calculateSoundexCode('Rupert'));    // R163
console.log(calculateSoundexCode('Rubin'));     // R150
console.log(calculateSoundexCode('Ashcraft'));  // A226
console.log(calculateSoundexCode('Ashcroft'));  // A226
console.log(calculateSoundexCode('Tymczak'));   // T522
console.log(calculateSoundexCode('Pfister'));   // P236
console.log(calculateSoundexCode('Honeyman'));  // H555

References

1. Soundex - Wikipedia

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