- When you create a object, in V8, it creates a hidden class to repesent the object shape.
- Two different objects with same object shape might share the same hidden class
- Any difference in object (prop order, more or less props) will result two different hidden class
- Keep a low number of hidden class can help with V8 performance.
Ideas:
- Always using factory function to create object. so that can keep the object shape the same everytime.
- Don't split object creation into multi steps, it will force V8 to create another hidden class
- Define all the possible props for object in one go, mark some props as undefined and change value later
- In Typescript, for an object
{name: string, company?: string}or{name: string, company: string | undefined }, which one to choose?- In most case they are the same
- But consider hidden class
{name: string, company: string | undefined }will be prefer approach {name: string, company: string | undefined }: means that company should be there, but can be undefined{name: string, company?: string}: means that company may not exist at all- Different means might results a difference in V8 preformance in the end.