http-proxy-middleware/dist/path-rewriter.js

The one-liner node.js proxy middleware for connect, express, next.js and more

import isPlainObject from 'is-plain-obj';
import { Debug } from './debug.js';
import { ERRORS } from './errors.js';
const debug = Debug.extend('path-rewriter');
/**
 * Create rewrite function, to cache parsed rewrite rules.
 */
export function createPathRewriter(rewriteConfig) {
    let rulesCache;
    if (!isValidRewriteConfig(rewriteConfig)) {
        return;
    }
    if (typeof rewriteConfig === 'function') {
        const customRewriteFn = rewriteConfig;
        return customRewriteFn;
    }
    else {
        rulesCache = parsePathRewriteRules(rewriteConfig);
        return rewritePath;
    }
    function rewritePath(path) {
        let result = path;
        for (const rule of rulesCache) {
            if (rule.regex.test(path)) {
                result = result.replace(rule.regex, rule.value);
                debug('rewriting path from "%s" to "%s"', path, result);
                break;
            }
        }
        return result;
    }
}
function isValidRewriteConfig(rewriteConfig) {
    if (typeof rewriteConfig === 'function') {
        return true;
    }
    else if (isPlainObject(rewriteConfig)) {
        return Object.keys(rewriteConfig).length !== 0;
    }
    else if (rewriteConfig === undefined || rewriteConfig === null) {
        return false;
    }
    else {
        throw new Error(ERRORS.ERR_PATH_REWRITER_CONFIG);
    }
}
function parsePathRewriteRules(rewriteConfig) {
    const rules = [];
    if (isPlainObject(rewriteConfig)) {
        for (const [key, value] of Object.entries(rewriteConfig)) {
            rules.push({
                regex: new RegExp(key),
                value: value,
            });
            debug('rewrite rule created: "%s" ~> "%s"', key, value);
        }
    }
    return rules;
}