如何启动可以访问 node.js 中的局部变量的 REPL？

Question

就像 from IPython import embed; embed() 但 node.

我想以编程方式打开 REPL shell 并且至少能够读取局部变量。能够改变它们也是一个加号。

Answer 1

对于deno（标题说Node.js，标记deno）你可以使用Deno.run执行deno并写入stdin并从[读取=16=].

执行以下操作：

const p = Deno.run({
    cmd: ["deno"],
    stdin: "piped",
    stdout: "piped",
    stderr: "piped"
  });

async function read(waitForMessage) {
    const reader = Deno.iter(p.stdout)
    let res = '';
    for await(const chunk of reader) {      
        res += new TextDecoder().decode(chunk);
        console.log('Chunk', res, '---')
        // improve this, you should wait until the last chunk 
        // is read in case of a command resulting in a big output
        if(!waitForMessage)
            return res;
        else if(res.includes(waitForMessage))
            return res;
    }
}

async function writeCommand(command) {
    const msg = new TextEncoder().encode(command + '\n'); 

    console.log('Command: ', command)
    const readPromise = read();
    // write command
    await p.stdin.write(msg);
    // Wait for output
    const value = await readPromise

    return value;
}

// Wait for initial output: 
// Deno 1.0.0
// exit using ctrl+d or close()
await read('ctrl+d or close()');


await writeCommand('let x = 5;')
let value = await writeCommand('x') // read x
console.log('Value: ', value)

await writeCommand('x = 6;')
value = await writeCommand('x') // read x
console.log('Value: ', value)

如果您运行该片段，输出将是：

Command: let x = 5;
Command: x
Value: 5

Command:  x = 6;
Command:  x
Value:  6

需要进行一些改进，例如处理 stderr 但您明白了。

Answer 2

此功能目前不存在，但在 https://github.com/denoland/deno/issues/7938 中提出。

愿景与

类似

Deno.eval("Deno.repl()")

Answer 3

您可以构建类似于内置 Deno REPL 的 REPL，并使用 dangerous eval function. Through it you'll be able to access local variables and other things (e.g. window).

计算表达式

repl.ts

import { readLines, writeAll } from "https://deno.land/std@0.106.0/io/mod.ts";

export default async function repl(evaluate: (x: string) => unknown) {
  await writeOutput("exit using ctrl+d or close()\n");
  await writeOutput("> ");
  for await (const input of readInputs()) {
    try {
      const value = evaluate(input);
      const output = `${Deno.inspect(value, { colors: !Deno.noColor })}\n`;
      await writeOutput(output);
      await writeOutput("> ");
    } catch (error) {
      await writeError(error);
    }
  }
}

async function* readInputs(): AsyncIterableIterator<string> {
  yield* readLines(Deno.stdin);
}

async function writeOutput(output: string) {
  await writeAll(Deno.stdout, new TextEncoder().encode(output));
}

async function writeError(error: unknown) {
  await writeAll(Deno.stderr, new TextEncoder().encode(`Uncaught ${error}\n`));
}

repl_demo.ts

import repl from "./repl.ts";

let a = 1;
let b = 2;
let c = 3;

await repl((x) => eval(x));

用法示例

% deno run repl_demo.ts
exit using ctrl+d or close()
> a
1
> a = 40
40
> a + b
42

Answer 4

据我所知，最接近的方法是使用 repl 内置模块（由 node inspect 本身使用）：

// ... your code you want to debug 

const repl = require("repl");
const replServer = repl.start({
    prompt: "Your Own Repl > ",
    useGlobal: true
});

// Expose variables
const localVar = 42    
replServer.context.localVar = localVar;

通过运行 node index.js（假设您将上述内容保存在 index.js 中）我们可以访问此自定义回复：

$ node index.js 
Your Own Repl > localVar
42
Your Own Repl > 
(To exit, press Ctrl+C again or Ctrl+D or type .exit)
Your Own Repl >

但是，这不像调试器工具那样工作，实际上，它只是一个 REPL。

Answer 5

const readline = require('readline');

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});
//to be sure this context is here
const ev = eval.bind(this);
function ask() {
     rl.question('>', (code) => {
           console.log(ev(code));
           ask();
     });
} 
ask();

此代码使用 readLine 模块请求输入，每次提供响应时都会执行代码并请求新的输入

如何启动可以访问 node.js 中的局部变量的 REPL？

How can I start a REPL that can access local variables in node.js?

javascript

node.js

read-eval-print-loop

deno