JavaScript 运行时 vs 编译时 All In One

JavaScript 运行时 vs 编译时 All In One

JavaScript / TypeScript

1. 编译器把源代码编译成机器可以识别的程序的编译过程，被称为编译时。

2. 编译后的程序被解释器执行的运行过程，被称为运行时。

JavaScript

Single-threaded
Non-blocking
Asynchronous
Concurrent

V8 Engine

Heap
where memory allocation happes.
Stack
To save the JS function programming.
On each new function call, it’s pushed on top of the stack
Web APIS
Extra thhings are the browser provides. DOM, AJAX, timeout etc
Callback Queue
When a process finished its job, such as a xhr call, it’s dropped in a callback queue.
Callback queue is triggered by event loop process after our stack is empty which means the process waits in that queue until our stack is empty.
Once our stack has no function call, then a process is popped-out from callback queue and pushed in to stack
Event loop
A process which is responsible to check our stack and then trigger our callback queue continuously.

The call stack

one thread == one call stack == one thing at a time

http://latentflip.com/loupe/?code=JC5vbignYnV0dG9uJywgJ2NsaWNrJywgZnVuY3Rpb24gb25DbGljaygpIHsKICAgIHNldFRpbWVvdXQoZnVuY3Rpb24gdGltZXIoKSB7CiAgICAgICAgY29uc29sZS5sb2coJ1lvdSBjbGlja2VkIHRoZSBidXR0b24hJyk7ICAgIAogICAgfSwgMjAwMCk7Cn0pOwoKY29uc29sZS5sb2coIkhpISIpOwoKc2V0VGltZW91dChmdW5jdGlvbiB0aW1lb3V0KCkgewogICAgY29uc29sZS5sb2coIkNsaWNrIHRoZSBidXR0b24hIik7Cn0sIDUwMDApOwoKY29uc29sZS5sb2coIldlbGNvbWUgdG8gbG91cGUuIik7!!!PGJ1dHRvbj5DbGljayBtZSE8L2J1dHRvbj4%3D

js 运行时 / js runtime

JavaScript Runtime, JavaScript 解释器的执行过程

js V8 engine

js 调用堆栈

JavaScript runtime environment.

JavaScript 运行时环境

Node.js
Deno

js 编译时 / js compile

JavaScript 编译器的执行过程

TypeScript, tsc complier

类型检查

// @ts-check

// 在 js 中使用 TypeScript 的类型检查功能

Rust & WebAssembly

demos

以 C 语言为例, .cpp => .out

源代码 => 目标代码 ==> 字节码(可执行文件 .exe) ?

C语言的执行过程, 目标代码

C语言的编译过程

gcc命令其实依次执行了四步操作：1.预处理(Preprocessing), 2.编译(Compilation), 3.汇编(Assemble), 4.链接(Linking)。

# 编译
$ gcc hello.c
# 执行
$ ./a.out
# hello world!

# 检查系统上是否安装了 GCC
$ gcc -v
Apple clang version 14.0.0 (clang-1400.0.29.202)
Target: x86_64-apple-darwin22.2.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

https://gcc.gnu.org/install/

https://developer.apple.com/xcode/

https://www.runoob.com/cprogramming/c-tutorial.html

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refs

https://www.cnblogs.com/CarpenterLee/p/5994681.html

https://blog.sessionstack.com/how-does-javascript-actually-work-part-1-b0bacc073cf

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