JavaScript Performance Prall

Reasons For JS Performance Issues

• Performance issues are non-linear. Big-O notation determines whether something scales:
  • Constant
  • Linear
  • Loglinear
  • Quadratic
  • Factorial
• CPU profiler = which functions are called, how often
• Don’t pre-optimize, you won’t know where your issues will be
• Don’t pass two types to one variable in a signature
  • No “type polymorphism”
  • Can’t be cached or optimized
• Don’t change existing objects, it ruins optimization
• Interpreted code runs on a VM, but can be cached
• Garbage collection
  • All context is retained from closures!
  • Profile memory to look for issues