Check any url is in safe parent domain without URL class. 检查任意URL是否在它的父级域下，不使用URL。

check-is-safe-parent-domain.js

function isSafeParentDomain(url, safeDomains) {
    try {
        // Using polyfill for String.prototype.endsWith
        if (!String.prototype.endsWith) {
            String.prototype.endsWith = function(search, this_len) {
                if (this_len === undefined || this_len > this.length) {
                    this_len = this.length;
                }
                return this.substring(this_len - search.length, this_len) === search;
            };
        }
        var defaultSafeDomains = ["example.com", "www.abc.com"];
        safeDomains = safeDomains || defaultSafeDomains;
        // tricky method
        var testHyperlink = document.createElement('a');
        testHyperlink.href = url;
        var flag = false;
        for (var i = 0; i < safeDomains.length; i++) {
            if (testHyperlink.hostname.endsWith(safeDomains[i])) {
                flag = true;
                break;
            }
        }
        return flag;
    } catch (e) {
        console.log("safe parent domain check failed, error:")
        console.log(e)
        // skip notice if failed.
        return true;
    }
}