1. A computer system configured to improve security of server computers interacting with client computers, and comprising: a memory; a processor coupled to the memory; and source code obfuscation logic coupled to the memory and the processor, and configured to: read, from the memory, one or more original source code instructions that are configured to achieve an expected result when executed by a web browser on a client computer; apply one or more obfuscation transformations, to the one or more original source code instructions, to produce one or more obfuscated source code instructions that are configured to achieve the same expected result when executed by the web browser but is expressed in an obfuscated format; and write the one or more obfuscated source code instructions to the memory; wherein the one or more original source code instructions comprise a literal; wherein the one or more obfuscated source code instructions comprise a statement defining a closure having a body that is configured to return the literal when executed by the web browser and an invocation of the closure, and which is configured to achieve the expected result when executed by the web browser.