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---
layout: page
title: "JavaScript metaphone function"
comments: true
sharing: true
footer: true
alias:
- /functions/view/metaphone:863
- /functions/view/metaphone
- /functions/view/863
- /functions/metaphone:863
- /functions/863
---
<!-- Generated by Rakefile:build -->
A JavaScript equivalent of PHP's metaphone
{% codeblock strings/metaphone.js lang:js https://raw.github.com/kvz/phpjs/master/functions/strings/metaphone.js raw on github %}
function metaphone (word, phones) {
// + original by: Greg Frazier
// + improved by: Brett Zamir (http://brett-zamir.me)
// + improved by: Rafał Kukawski (http://kukawski.pl)
// * example 1: metaphone('Gnu');
// * returns 1: 'N'
word = (word == null ? '' : word + '').toUpperCase();
function isVowel (a) {
return 'AEIOU'.indexOf(a) !== -1;
}
function removeDuplicates (word) {
var wordlength = word.length,
char1 = word.charAt(0),
char2,
rebuilt = char1;
for (var i = 1; i < wordlength; i++) {
char2 = word.charAt(i);
if (char2 !== char1 || char2 === 'C' || char2 === 'G') { // 'c' and 'g' are exceptions
rebuilt += char2;
}
char1 = char2;
}
return rebuilt;
}
word = removeDuplicates(word);
var wordlength = word.length,
x = 0,
metaword = '';
//Special wh- case
if (word.substr(0, 2) === 'WH') {
// Remove "h" and rebuild the string
word = 'W' + word.substr(2);
}
var cc = word.charAt(0); // current char. Short name cause it's used all over the function
var pc = ''; // previous char. There is none when x === 0
var nc = word.charAt(1); // next char
var nnc = ''; // 2 characters ahead. Needed later
if (1 <= wordlength) {
switch (cc) {
case 'A':
if (nc === 'E') {
metaword += 'E';
} else {
metaword += 'A';
}
x += 1;
break;
case 'E': case 'I': case 'O': case 'U':
metaword += cc;
x += 1;
break;
case 'G': case 'K': case 'P':
if (nc === 'N') {
x += 1;
}
break;
case 'W':
if (nc === 'R') {
x += 1;
}
break;
}
}
for (; x < wordlength; x++) {
cc = word.charAt(x);
pc = word.charAt(x - 1);
nc = word.charAt(x + 1);
nnc = word.charAt(x + 2);
if (!isVowel(cc)) {
switch (cc) {
case 'B':
if (pc !== 'M') {
metaword += 'B';
}
break;
case 'C':
if (x + 1 <= wordlength) {
if (word.substr(x - 1, 3) !== 'SCH') {
if (x === 0 && (x + 2 <= wordlength) && isVowel(nnc)) {
metaword += 'K';
} else {
metaword += 'X';
}
} else if (word.substr(x + 1, 2) === 'IA') {
metaword += 'X';
} else if ('IEY'.indexOf(nc) !== -1) {
if (x > 0) {
if (pc !== 'S') {
metaword += 'S';
}
} else {
metaword += 'S';
}
} else {
metaword += 'K';
}
} else {
metaword += 'K';
}
break;
case 'D':
if (x + 2 <= wordlength && nc === 'G' && 'EIY'.indexOf(nnc) !== -1) {
metaword += 'J';
x += 2;
} else {
metaword += 'T';
}
break;
case 'F':
metaword += 'F';
break;
case 'G':
if (x < wordlength) {
if ((nc === 'N' && x + 1 === wordlength - 1) || (nc === 'N' && nnc === 'S' && x + 2 === wordlength - 1)) {
break;
}
if (word.substr(x + 1, 3) === 'NED' && x + 3 === wordlength - 1) {
break;
}
if (word.substr(x - 2, 3) === 'ING' && x === wordlength - 1) {
break;
}
if (x + 1 <= wordlength - 1 && word.substr(x - 2, 4) === 'OUGH') {
metaword += 'F';
break;
}
if (nc === 'H' && x + 2 <= wordlength) {
if (isVowel(nnc)) {
metaword += 'K';
}
} else if (x + 1 === wordlength) {
if (nc !== 'N') {
metaword += 'K';
}
} else if (x + 3 === wordlength) {
if (word.substr(x + 1, 3) !== 'NED') {
metaword += 'K';
}
} else if (x + 1 <= wordlength) {
if ('EIY'.indexOf(nc) !== -1) {
if (pc !== 'G') {
metaword += 'J';
}
} else if (x === 0 || pc !== 'D' || 'EIY'.indexOf(nc) === -1) {
metaword += 'K';
}
} else {
metaword += 'K';
}
} else {
metaword += 'K';
}
break;
case 'M': case 'J': case 'N': case 'R': case 'L':
metaword += cc;
break;
case 'Q':
metaword += 'K';
break;
case 'V':
metaword += 'F';
break;
case 'Z':
metaword += 'S';
break;
case 'X':
metaword += (x === 0) ? 'S' : 'KS';
break;
case 'K':
if (x === 0 || pc !== 'C') {
metaword += 'K';
}
break;
case 'P':
if (x + 1 <= wordlength && nc === 'H') {
metaword += 'F';
} else {
metaword += 'P';
}
break;
case 'Y':
if (x + 1 > wordlength || isVowel(nc)) {
metaword += 'Y';
}
break;
case 'H':
if (x === 0 || 'CSPTG'.indexOf(pc) === -1) {
if (isVowel(nc) === true) {
metaword += 'H';
}
}
break;
case 'S':
if (x + 1 <= wordlength) {
if (nc === 'H') {
metaword += 'X';
} else if (x + 2 <= wordlength && nc === 'I' && 'AO'.indexOf(nnc) !== -1) {
metaword += 'X';
} else {
metaword += 'S';
}
} else {
metaword += 'S';
}
break;
case 'T':
if (x + 1 <= wordlength) {
if (nc === 'H') {
metaword += '0';
} else if (x + 2 <= wordlength && nc === 'I' && 'AO'.indexOf(nnc) !== -1) {
metaword += 'X';
} else {
metaword += 'T';
}
} else {
metaword += 'T';
}
break;
case 'W':
if (x + 1 <= wordlength && isVowel(nc)) {
metaword += 'W';
}
break;
}
}
}
phones = parseInt(phones, 10);
if (metaword.length > phones) {
return metaword.substr(0, phones);
}
return metaword;
}
{% endcodeblock %}
- [Raw function on GitHub](https://github.com/kvz/phpjs/blob/master/functions/strings/metaphone.js)
Please note that php.js uses JavaScript objects as substitutes for PHP arrays, they are
the closest match to this hashtable-like data structure.
Please also note that php.js offers community built functions and goes by the
[McDonald's Theory](https://medium.com/what-i-learned-building/9216e1c9da7d). We'll put online
functions that are far from perfect, in the hopes to spark better contributions.
Do you have one? Then please just:
- [Edit on GitHub](https://github.com/kvz/phpjs/edit/master/functions/strings/metaphone.js)
### Example 1
This code
{% codeblock lang:js example %}
metaphone('Gnu');
{% endcodeblock %}
Should return
{% codeblock lang:js returns %}
'N'
{% endcodeblock %}
### Other PHP functions in the strings extension
{% render_partial _includes/custom/strings.html %}