everyutil/string/stringSimilarity.js

A comprehensive library of lightweight, reusable utility functions for JavaScript and TypeScript, designed to streamline common programming tasks such as string manipulation, array processing, date handling, and more.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.stringSimilarity = void 0;
/**
 * Returns a similarity score between two strings (0..1, Levenshtein-based).
 *
 * Uses normalized Levenshtein distance: 1 means identical, 0 means completely different.
 * Example: stringSimilarity("kitten", "sitting") → 0.714
 *
 * @author @dailker
 * @param {string} a - First string.
 * @param {string} b - Second string.
 * @returns {number} Similarity score between 0 and 1.
 */
function stringSimilarity(a, b) {
    if (a === b)
        return 1;
    const m = a.length, n = b.length;
    if (m === 0 || n === 0)
        return 0;
    const dp = Array.from({ length: m + 1 }, () => Array(n + 1).fill(0));
    for (let i = 0; i <= m; i++)
        dp[i][0] = i;
    for (let j = 0; j <= n; j++)
        dp[0][j] = j;
    for (let i = 1; i <= m; i++) {
        for (let j = 1; j <= n; j++) {
            dp[i][j] = Math.min(dp[i - 1][j] + 1, dp[i][j - 1] + 1, dp[i - 1][j - 1] + (a[i - 1] === b[j - 1] ? 0 : 1));
        }
    }
    const dist = dp[m][n];
    return 1 - dist / Math.max(m, n);
}
exports.stringSimilarity = stringSimilarity;