The disclosure provides a method for executing extended JavaScript (JS) by using an extended JS interface. The method includes the following steps: inquiring an extension program whether to execute the extended JS at a predetermined occasion when a webpage is loaded, wherein the extension program is loaded when a browser is started up; the browser assembles the extended JS interface according to an open application programming interface (API) when determining that the extended JS is needed to be executed; executing the extended JS by using the extended JS interface. According to the disclosure, browsing mode and layout mode of a browser can be changed dynamically according to the requirement for webpage contents in the form of extension programs, accordingly browsing experience of users is improved.