JavaScript Cheat Sheet

Performance Tips

• Module loading can help if loading JS files from a remote server is causing slowdowns. Asynchronous module loading can help reduce latency. (Cozzi ch. 4.2).
• Don't dynamically add properties to objects. (Cozzi ch. 4.3)
• Object.create is slower than calling new. Object literal notation is almost as fast as new, as long as functions are cached in a parent scope to avoid re-creating the functions every time we create an object. (Cozzi ch. 4.3.1).
• Computing intermediate values that are quickly thrown away (e.g. vec3 object for linear algebra math) causes problems because unlike with other languages like C++ they don't live on the stack. Therefore, they can incur significant garbage collection overhead. (Cozzi ch. 4.3.2)
  • GC issues can manifest as a "sawtooth" pattern in a heap usage graph in a profile. (Cozzi fig. 4.2)
  • Avoid these issues by having users pass in already-allocated result parameters, and using module-scoped scratch parameters to reduce the number of allocations. (Cozzi listing 4.8)
• Passing large amounts of data between Web Workers can be very slow because by default, they pass by copy. The Transferable object helps us avoid this problem. (Cozzi ch. 4.3.3).

Sources Cited

1. Cozzi, Patrick et al. WebGL Insights.