Javascript 优化、V8 引擎和 Typescript

Question

I read the following article about V8 engine and javascript optimization.

How JavaScript works: inside the V8 engine + 5 tips on how to write optimized code

According to above article, these are recommended :

a. V8 engine uses hidden classes and caching mechanism for the hidden classes and properties. So avoid dynamically adding object properties, and avoid dynamically changing the type of properties. Instead use object constructor function.

b.V8 engine applies more optimizations to frequently used functions. So avoid generating many different similar form functions executed only once. Instead write code to repeatedly execute same function.

Then, I have 3 questions :

i. Can 'a' and 'b' be applied to other browser's javascript engine, such as firefox's SpiderMonkey?

ii. According to 'a', using typescript is more advantageous for v8 engine optimization? (Using typescript, you can generate javascript code with fewer dynamically changing objects and properties)

iii. Modern JavaScript code uses a lot of inline and anonymous functions having similar form, like the example code below. According to 'b', using single predefined function is more advantageous instead? (This example code is very simplified one to show similar form functions used many times)

prm.then((res) => {
    console.log(res);
}).then((res2) => {
    console.log(res2);
}).catch((err) => {
    console.log(err);
});

Answer 1

First off your title is very weak. Titles should be almost in the form of a question. For example: "Is it possible to optimize code for javascript engines?"

Can 'a' and 'b' be applied to other browser's javascript engine, such as firefox's SpiderMonkey?

Sure, but that's up to the developers of those engines to do so. I don't think asking it here has any benefit.

According to 'a', using typescript is more advantageous for v8 engine optimization?

Typescript is compiled into Javascript. V8 is a Javascript engine, so believing that the compiler for typescript is doing anything different for V8 OR V8 is doing any optimizations because it some how magically knows the Javascript came from Typescript, that any advantageous would be speculation at best (unless someone who is familiar with the code knows otherwise).

Since the TypeScript compiler is attempting to write good/optimized Javascript code anyway, V8 is simply taking advantage of good code. Anyone can write good Javascript, it's just simply harder to write bad TypeScript. But it's important to note that because Typescript compiles code the same way everytime, V8 can take advantage of that, but it's only beneficial if a programmer likes writing in Typescript.

Modern JavaScript code uses a lot of inline and anonymous functions having similar form, like the example code below. According to 'b', using single predefined function is more advantageous instead?

Advantageous in what way?

Your anonymous functions are most likely already compiled out as console.log() is the only thing being called and could easily be in-lined. So it's really a bad example.

As for functions that would be more complex, writing a single function is already a good principle to adhere to anyway ( Don't Repeat Yourself - DRY ). So any programmer who keeps code DRY won't have any thing to really worry about because they've already written good code to begin with and subsequently V8 takes advantage of that.

Regardless of engine, it seems that the answer really is just write good code .