Add whitelist domain which automatically receive url params

Add whitelist params to append

This script append url's specific params to all link on your page. For example: user come to your site at url: example.com/landing-page?utm_source=abc_referral, this script append "utm_source=abc_referral" to all links on example.com/landing-page.

Usecase: forward utm... params to internal link so you can keep tracking source.

(function () {
            var domainsToDecorate = [
                    "letweb.net"
                ],
                queryParams = [
                    "utm_medium",
					"utm_source",
					"utm_campaign"
                ];
            // do not edit anything below this line
            var links = document.querySelectorAll("a");

// check if links contain domain from the domainsToDecorate array and then decorates
            for (var linkIndex = 0; linkIndex < links.length; linkIndex++) {
                for (
                    var domainIndex = 0;
                    domainIndex < domainsToDecorate.length;
                    domainIndex++
                ) {
                    if (
                        links[linkIndex].href.indexOf(
                            domainsToDecorate[domainIndex]
                        ) > -1 &&
                        links[linkIndex].href.indexOf("#") === -1
                    ) {
                        links[linkIndex].href = decorateUrl(
                            links[linkIndex].href
                        );
                    }
                }
            }
            // decorates the URL with query params
            function decorateUrl(urlToDecorate) {
                urlToDecorate =
                    urlToDecorate.indexOf("?") === -1
                        ? urlToDecorate + "?"
                        : urlToDecorate + "&";
                var collectedQueryParams = [];
                for (
                    var queryIndex = 0;
                    queryIndex < queryParams.length;
                    queryIndex++
                ) {
                    if (getQueryParam(queryParams[queryIndex])) {
                        collectedQueryParams.push(
                            queryParams[queryIndex] +
                                "=" +
                                getQueryParam(queryParams[queryIndex])
                        );
                    }
                }
                return urlToDecorate + collectedQueryParams.join("&");
            }

// borrowed from https://stackoverflow.com/questions/831030/
            // a function that retrieves the value of a query parameter
            function getQueryParam(name) {
                if (
                    (name = new RegExp(
                        "[?&]" + encodeURIComponent(name) + "=([^&]*)"
                    ).exec(window.location.search))
                )
                    return decodeURIComponent(name[1]);
            }
        })()

About this source code

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