locutus
Version:
Locutus other languages' standard libraries to JavaScript for fun and educational purposes
50 lines (49 loc) • 2.07 kB
JavaScript
export function similar_text(first, second, percent) {
// discuss at: https://locutus.io/php/similar_text/
// parity verified: PHP 8.3
// original by: Rafał Kukawski (https://blog.kukawski.pl)
// bugfixed by: Chris McMacken
// bugfixed by: Jarkko Rantavuori original by findings in stackoverflow (https://stackoverflow.com/questions/14136349/how-does-similar-text-work)
// improved by: Markus Padourek (taken from https://www.kevinhq.com/2012/06/php-similartext-function-in-javascript_16.html)
// example 1: similar_text('Hello World!', 'Hello locutus!')
// returns 1: 8
// example 2: similar_text('Hello World!', null)
// returns 2: 0
if (first === null || second === null || typeof first === 'undefined' || typeof second === 'undefined') {
return 0;
}
const firstValue = String(first);
const secondValue = String(second);
let pos1 = 0;
let pos2 = 0;
let max = 0;
const firstLength = firstValue.length;
const secondLength = secondValue.length;
let sum = 0;
for (let p = 0; p < firstLength; p++) {
for (let q = 0; q < secondLength; q++) {
let l = 0;
for (l = 0; p + l < firstLength && q + l < secondLength && firstValue.charAt(p + l) === secondValue.charAt(q + l); l++) {
// @todo: ^-- break up this crazy for loop and put the logic in its body
}
if (l > max) {
max = l;
pos1 = p;
pos2 = q;
}
}
}
sum = max;
if (sum) {
if (pos1 && pos2) {
sum += similar_text(firstValue.substr(0, pos1), secondValue.substr(0, pos2));
}
if (pos1 + max < firstLength && pos2 + max < secondLength) {
sum += similar_text(firstValue.substr(pos1 + max, firstLength - pos1 - max), secondValue.substr(pos2 + max, secondLength - pos2 - max));
}
}
if (!percent) {
return sum;
}
return (sum * 200) / (firstLength + secondLength);
}