Semantics for ECMAScript 5.0

Install and Usage

See INSTALL for installation instruction.

s5 options are implemented as stack manipulation so the order of options matters. Here are a few examples (in src/ directory, and a js file test.js exists):

Desugar a Javascript program and print the S5 source.

$ ./s5.d.byte -desugar test.js -print-src

Desugar a Javascript program, wrap with an Environment and do evaluation.

$ ./s5.d.byte -desugar test.js -env ../envs/es5.env -apply -eval

Desugar a Javascript program, wrap with an Environment, apply optimizations and finally print out the optimized code (excluding the environment).

$ ./s5.d.byte -desugar test.js -env ../envs/es5-optimization.env -apply -opt-restore-id -opt-restore-function -opt-propagate-const -opt-clean-deadcode -print-user-s5

Slimming Language Options

All optimization options start with "-opt-". There are a few options not compatible with the optimization flags:

1. -internal-env env-vars. This option introduces identifiers of es5.env in the nested environment for eval. It has a huge negative impact on the constant propagation.
2. -env es5.env. There are several env files in env/ directory. Optimization flags only work on es5-optimization.env, which is similar to es5.env. The only difference is that it excludes built-in eval support (-opt-restore-id would not work if es5.env is used). See previous usage examples for how to pass a correct environment.