jkdb
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javascript interface for kdb+/q
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# jkdb
[](https://www.npmjs.com/package/jkdb)
A zero dependency javascript Node.js package to interface with kdb+/q (v2.6+).
## Installation
```
npm install --save-dev jkdb
```
## Quick Start
### Connect to a q Process
```javascript
const { QConnection } = require("jkdb");
const q = new QConnection({ port: 1800 });
q.connect((err) => {
if (err) throw err;
console.log("connected");
// send query from here
});
```
### Connect to a TLS-protected q Process
```javascript
const { QConnection } = require("jkdb");
const q = new QConnection({ port: 1800, useTLS: true });
q.connect((err) => {
if (err) throw err;
console.log("connected");
// send query from here
});
```
### Connect to a q Process with Credentials
```javascript
const { QConnection } = require("jkdb");
const q = new QConnection({ port: 1800, user: "user", password: "password" });
q.connect((err) => {
if (err) throw err;
console.log("connected");
// send query from here
});
```
### Send a Sync Query
```javascript
q.sync("(+/) til 10", (err, res) => {
if (err) throw err;
console.log("result: ", res);
// result: 45
});
```
### Send a Sync Function Call
```javascript
q.sync(["(*/)", [22, 27, 45]], (err, res) => {
if (err) throw err;
console.log("result: ", res);
// result: 26730
});
```
### Send a Sync Function Call with Multiple Parameters
```javascript
q.sync(
[
"mmu",
[1, 2, 3],
[
[1, 2, 3],
[4, 5, 6],
[7, 8, 9],
],
],
(err, res) => {
if (err) throw err;
console.log("result: ", res);
// result: 30,36,42
}
);
```
### Send an Async Query
```javascript
q.asyn("show 99", (err) => {
if (err) throw err;
});
```
### Send an Async Function Call
```javascript
q.asyn(["show", 99], (err) => {
if (err) throw err;
});
```
### Subscribe
```javascript
q.on("upd", (table, data) => {
console.log(table, data);
});
q.sync(".u.sub[`trade;`7203.T]", (err, _res) => {
if (err) throw err;
});
```
### Close q Connection
```javascript
q.close(() => {
console.log("closed");
});
```
## Date Types
### Deserialization
Deserialization of long and timestamp can be controlled by QConnection arguments `useBigInt` and `includeNanosecond`.
| k type | argument | javascript type | k null | infinity | -infinity |
| ---------- | ----------------- | --------------- | -------------------------------- | -------- | --------- |
| boolean | | Boolean | | | |
| guid | | String | 00000000000000000000000000000000 | | |
| byte | | Number | | | |
| short | | Number | NaN | Infinity | -Infinity |
| int | | Number | NaN | Infinity | -Infinity |
| long | | Number | NaN | Infinity | -Infinity |
| long | useBigInt | BigInt | NaN | Infinity | -Infinity |
| real | | Number | NaN | Infinity | -Infinity |
| float | | Number | NaN | Infinity | -Infinity |
| char | | String | ' ' | | |
| symbol | | String | '' | | |
| timestamp | | Date | null | null | null |
| timestamp | includeNanosecond | String | '' | '' | '' |
| month | | String | null | null | null |
| date | | Date | null | null | null |
| date | dateToMillisecond | Number | NaN | Infinity | -Infinity |
| datetime | | Date | null | null | null |
| datetime | dateToMillisecond | Number | NaN | Infinity | -Infinity |
| timespan | | String | null | null | null |
| minute | | String | null | null | null |
| second | | String | null | null | null |
| time | | String | null | null | null |
| dict | | Object | | | |
| list | | Array | | | |
| table | | Object | | | |
| lambda | | String | | | |
| projection | | Array | | | |
### Serialization
#### Atom
| javascript type | k type |
| --------------- | --------- |
| Boolean | boolean |
| Number | float |
| String | chars |
| Date | timestamp |
#### Array
| javascript type | Symbol.for('kType') | k type |
| --------------- | ------------------- | --------- |
| Boolean Array | b | boolean |
| String Array | g | guid |
| Number Array | i | int |
| Number Array | j | long |
| Number Array | f | float |
| String Array | c | char |
| String Array | s | symbol |
| Date Array | p | timestamp |
| Date Array | d | date |
| Date Array | z | datetime |
Use `Symbol.for('kType')` to specify k type for the array, e.g.
```javascript
const ints = [99, 11, 3, 3];
ints[Symbol.for("kType")] = "j";
```
#### Object without meta
Convert to a dictionary, keys are symbols, e.g.
```javascript
const dict = { sym: "8306.T", price: 668.2 };
```
#### Object with meta
Convert to a table, e.g.
```javascript
const table = {
sym: ["AXJO", "AXJO"],
date: [new Date("2021-05-13"), new Date("2021-05-14")],
open: [7000, 6000],
};
table[Symbol.for("meta")] = {
c: ["sym", "date", "open"],
t: ["s", "d", "f"],
};
```