mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-10-21 05:50:55 +08:00
Chris Tate
e517a251ae
- Preserve class property views, opaque record identity, and nullable structural conversions - Run package metadata transforms and TypeScript option merges as native code - Serialize live typed records with opaque payloads and JSON hooks
71 lines
3.1 KiB
TypeScript
71 lines
3.1 KiB
TypeScript
// The object type proves that a value is not a primitive. It does not
|
|
// prove that the value has no enumerable fields, even though keyof is never.
|
|
function show(value: unknown): void {
|
|
if (value === null || typeof value !== "object" || Array.isArray(value)) return;
|
|
for (const [key, entry] of Object.entries(value)) {
|
|
console.log(key, typeof entry, JSON.stringify(entry));
|
|
}
|
|
console.log(Object.values(value).map((entry) => typeof entry).join(","));
|
|
}
|
|
show(JSON.parse('{"name":"package","version":2,"active":true,"missing":null,"nested":{"value":3}}'));
|
|
show(JSON.parse('{}'));
|
|
show(null);
|
|
show([1, 2]);
|
|
|
|
function dictionary(value: object): Record<string, unknown> {
|
|
const out: Record<string, unknown> = {};
|
|
for (const [key, entry] of Object.entries(value)) out[key] = entry;
|
|
return out;
|
|
}
|
|
console.log(JSON.stringify(dictionary(JSON.parse('{"a":"first","b":false}'))));
|
|
const opaque: object = JSON.parse('{"left":[1,2],"right":{"value":3}}');
|
|
const entries = Object.entries(opaque);
|
|
const values = Object.values(opaque);
|
|
console.log(entries.length, values.length, entries[0]?.[1] === values[0]);
|
|
console.log(JSON.stringify(entries));
|
|
|
|
// A declared shape keeps its useful value type.
|
|
const numbers = { first: 2, second: 3 };
|
|
console.log(Object.values(numbers).reduce((sum, number) => sum + number, 0));
|
|
console.log(Object.entries(numbers).map(([key, number]) => key + ":" + (number * 2)).join(","));
|
|
|
|
// An unchecked key keeps JavaScript's property spelling when absent.
|
|
const names = ["present"];
|
|
const open: Record<string, unknown> = {};
|
|
open[names[0]!] = 1;
|
|
const missing = names[3];
|
|
open[missing] = 2;
|
|
console.log(JSON.stringify(open));
|
|
console.log(open[missing]);
|
|
|
|
function selected(flag: boolean, value: Record<string, unknown>): void {
|
|
const presentFirst = flag ? Object.entries(value).filter(([, item]) => item !== null) : [];
|
|
const emptyFirst = flag ? [] : Object.entries(value).filter(([, item]) => item !== null);
|
|
console.log(JSON.stringify(Object.fromEntries(presentFirst)));
|
|
console.log(JSON.stringify(Object.fromEntries(emptyFirst)));
|
|
console.log(JSON.stringify(Object.fromEntries(Object.entries(value).filter(([, item]) => item !== null))));
|
|
}
|
|
selected(true, { left: 1, absent: null, right: "two" });
|
|
selected(false, { left: 1, absent: null, right: "two" });
|
|
|
|
// Entry tuples can live in either the native tuple layout or the dynamic
|
|
// array returned by enumeration. Both retain Array.prototype.join behavior.
|
|
console.log(Object.entries(opaque)[0].join(":"));
|
|
console.log(Object.entries(numbers)[1].join("="));
|
|
const tuple: [string, unknown, null, undefined] = ["key", true, null, undefined];
|
|
console.log(tuple.join(), tuple.join(undefined), tuple.join("|"));
|
|
let receiverCalls = 0;
|
|
function tupleReceiver(): [string, unknown, null, undefined] {
|
|
receiverCalls++;
|
|
return tuple;
|
|
}
|
|
function separator(): string {
|
|
tuple[1] = 42;
|
|
return ":";
|
|
}
|
|
console.log(tupleReceiver().join(separator()), receiverCalls);
|
|
const rows: [string, number][] = [["first", 1], ["second", 2]];
|
|
console.log(rows[1].join("="));
|
|
try { console.log(rows[9].join()); }
|
|
catch (error) { console.log(error instanceof TypeError); }
|