1. A method, comprising: intercepting, at a client during execution of an application at a browser on the client, a JavaScript call, wherein a source code of the application indicates a timed sequence of execution of JavaScript files, wherein the JavaScript files comprise a first JavaScript file loaded into the client's memory element simultaneously with loading the application, a second JavaScript file having a dependency on the first JavaScript file and called during the timed sequence after the first JavaScript file is called, and a third JavaScript file not called after a certain duration of the timed sequence; accessing, by the client, a map file stored at a server upon intercepting the JavaScript call, wherein the map file is generated automatically at the server before execution of the application on the client, wherein the map file includes a dependency tree comprising the JavaScript files used in the source code, wherein the first JavaScript file is specified in an exclusion file, wherein the map file maps the second JavaScript file for lazy loading, wherein the map file maps Cascading Style Sheets (CSS) files with related map for class names to be used on the application; reverse mapping from the map file, at the client during runtime of the application, particular JavaScript files corresponding the JavaScript call, wherein the reverse mapping comprises checking the JavaScript call for dependency resolution according to the map file, wherein a resolution scope of lazily loaded files ends with first-level dependencies of such files, wherein the particular JavaScript files are selected for loading according to the dependency resolution; loading the particular JavaScript files from the server into the client's memory element according to the exclusion file and the map file, wherein the loading comprises loading the first JavaScript file according to the exclusion file, lazy loading the second JavaScript file asynchronously with timestamp according to the map file, and reverse mapping relevant CSS files in the loaded files using related class names from the map file; and deleting, during application execution, the third JavaScript file from the client's memory element after the certain duration of the timed sequence.