csv-async-generator
v1.0.8
Published
A tiny CSV library to serialize and deserialize in a performant way. You can take a look at the kind of memory problems it can solve at [serialize-async-generator.test.ts](src/__tests__/serialize-async-generator.test.ts).
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CSV Async Generator
A tiny CSV library to serialize and deserialize in a performant way. You can take a look at the kind of memory problems it can solve at serialize-async-generator.test.ts.
Usage
Basic
expect(
serialize(
[
{ propA: "A1", propB: "B1" },
{ propA: "A2", propB: "B2" },
],
[
{ header: "A", cell: (item) => item.propA },
{ header: "B", cell: (item) => item.propB },
],
),
).toBe("A;B\r\n" + "A1;B1\r\n" + "A2;B2\r\n");
Advanced
const getPositiveNumbers = async function* () {
let number = 1;
while (true) {
yield Promise.resolve(number);
number++;
}
};
const limit = async function* <Item>(items: AsyncIterable<Item>, max: number) {
let count = 0;
for await (const item of items) {
if (count >= max) {
return;
}
yield item;
count++;
}
};
const filter = async function* <Item>(
items: AsyncIterable<Item>,
predicate: (item: Item) => any,
) {
for await (const item of items) {
if (predicate(item)) {
yield item;
}
}
};
const map = async function* <Input, Output>(
items: AsyncIterable<Input>,
mapper: (item: Input) => Output,
) {
for await (const item of items) {
yield mapper(item);
}
};
const getFirstFiveEvenPositiveNumbersAsItems = () =>
map(
limit(
filter(getPositiveNumbers(), (it) => it % 2),
5,
),
(it) => ({ value: String(it) }),
);
const lines: Array<string> = [];
for await (const line of serializeAsyncGenerator(
getFirstFiveEvenPositiveNumbersAsItems(),
[{ header: "Value", cell: (item) => item.value }],
)) {
lines.push(line);
}
expect(lines).toStrictEqual([
"Value\r\n",
"1\r\n",
"3\r\n",
"5\r\n",
"7\r\n",
"9\r\n",
]);