Sonarr/src/UI/polyfills.js

window.console = window.console || {};
window.console.log = window.console.log || function() {};
window.console.group = window.console.group || function() {};
window.console.groupEnd = window.console.groupEnd || function() {};
window.console.debug = window.console.debug || function() {};
window.console.warn = window.console.warn || function() {};
window.console.assert = window.console.assert || function() {};

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);
    };
}