mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-11-02 07:43:42 +08:00
Chris Tate
f521dc91b1
A top-level return in a CommonJS module compiles when declarations follow it. When the return is taken, only code that already exists can observe the bindings it skips: functions and classes created before the return, and function declarations after it. A module where one of them reads a binding declared after the return, or that assigns exports after it, still stops with SC1090. assert.strictEqual and assert.notStrictEqual compare a nullable number, string or boolean (`number | null`, `string | null`) with a scalar, null or undefined through the checked-dynamic SameValue compare, which reports Node's failure messages. notStrictEqual of another nullable value, such as `child.stdin`, against null or undefined tests the value's tag. An initializer-less JavaScript `let` whose writes all agree also takes their type when the writes are calls declared in the standard library, such as `spawn(...)`, and at file scope. A runtime handle that a closure captures takes the handle or undefined. Inside a nested function, a member read on it (`c.address()`, `child.stdin`) reads the handle and throws Node's TypeError while the binding is still undefined; other reads there take the checked-dynamic value.
47 lines
1.5 KiB
JavaScript
47 lines
1.5 KiB
JavaScript
// An initializer-less `let` assigned a child process on every branch keeps
|
|
// the child's type, including when callbacks read it, as Node's
|
|
// child_process tests do when they choose a command per platform.
|
|
const { spawn } = require('child_process');
|
|
|
|
let child;
|
|
if (process.platform === 'win32') child = spawn('cmd.exe', ['/c', 'echo', 'hi']);
|
|
else child = spawn('echo', ['hi']);
|
|
let text = '';
|
|
child.stdout.on('data', (chunk) => {
|
|
text += chunk;
|
|
});
|
|
|
|
let producer, consumer;
|
|
if (process.platform === 'win32') {
|
|
producer = spawn('cmd.exe', ['/c', 'echo', 'hello&&', 'echo', 'node']);
|
|
consumer = spawn('findstr', ['o']);
|
|
} else {
|
|
producer = spawn('printf', ['hello\nnode\nand\nworld\n']);
|
|
consumer = spawn('grep', ['o']);
|
|
}
|
|
producer.stdout.on('data', (data) => {
|
|
if (!consumer.stdin.write(data)) producer.stdout.pause();
|
|
});
|
|
consumer.stdin.on('drain', () => producer.stdout.resume());
|
|
producer.stdout.on('end', () => consumer.stdin.end());
|
|
let piped = '';
|
|
consumer.stdout.on('data', (data) => {
|
|
piped += data.toString('utf8', 0, data.length);
|
|
});
|
|
|
|
let quiet;
|
|
if (process.platform === 'win32') quiet = spawn('cmd.exe', ['/c', 'echo', 'quiet']);
|
|
else quiet = spawn('echo', ['quiet']);
|
|
quiet.stdout.setEncoding('utf8');
|
|
quiet.stdout.resume();
|
|
|
|
let count;
|
|
if (process.argv.length > 10) count = Math.max(1, 2);
|
|
else count = Math.min(3, 4);
|
|
console.log(count.toFixed(1));
|
|
|
|
process.on('exit', () => {
|
|
console.log(JSON.stringify(text), JSON.stringify(piped));
|
|
console.log(child.exitCode, producer.exitCode, consumer.exitCode, consumer.signalCode, quiet.exitCode);
|
|
});
|