Readarr/UI/polyfills.js

if (!String.prototype.startsWith) {
    Object.defineProperty(String.prototype, 'startsWith', {
        enumerable: false,
        configurable: false,
        writable: false,
        value: function (searchString, position) {
            position = position || 0;
            return this.indexOf(searchString, position) === position;
        }
    });
}

if (!String.prototype.endsWith) {
    Object.defineProperty(String.prototype, 'endsWith', {
        enumerable: false,
        configurable: false,
        writable: false,
        value: function (searchString, position) {
            position = position || this.length;
            position = position - searchString.length;
            var lastIndex = this.lastIndexOf(searchString);
            return lastIndex !== -1 && lastIndex === position;
        }
    });
}

if(!('contains' in String.prototype))
{
    String.prototype.contains = function(str, startIndex) {
        return -1 !== String.prototype.indexOf.call(this, str, startIndex);
    };
}