Here you can find the source of utc(func)
Date.prototype.utc = function(func) { "use strict"; return new Date(this.getUTCFullYear(), this.getUTCMonth(), this.getUTCDate(), this.getUTCHours(), this.getUTCMinutes(), this.getUTCSeconds()); };
Date.prototype.utc = function(){ return new Date(); };
Date.prototype.utcZero = function(){ return new Date(this.getTime() + this.getTimezoneOffset()*60*1000); };
Date.prototype.getTimeUTC = function () { return this.getTime() + this.getTimezoneOffset() * 60 * 1000; };
Date.prototype.getUTCFullDate = function() { return this.getUTCFullYear() + '-' + (this.getUTCMonth() + 1) + '-' + this.getUTCDate(); };
Date.prototype.getUtcDateObject = function () { return new Date(this.toUTCString());