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JavaScript Virtual Machine

Different engines have different “codenames”. For example:

How do engines work?

  1. The engine (embedded if it’s a browser) reads (“parses”) the script.
  2. Then it converts (“compiles”) the script to the machine language.
  3. And then the machine code runs, pretty fast.

The engine applies optimizations at each step of the process. It even watches the compiled script as it runs, analyzes the data that flows through it, and further optimizes the machine code based on that knowledge.