Queue a number of async functions which get executed sequentially.
Example:
const { Queue } = require('qfunc');
const queue = new Queue();
queue.enqueue(async () => {
await new Promise(resolve => setTimeout(resolve, 1000));
console.log('A');
});
queue.enqueue(async () => {
await new Promise(resolve => setTimeout(resolve, 500));
console.log('B');
});Output:
A
B
Enqueue any number of functions in a FIFO queue and they will run sequentially, awaiting the completion of each before starting the next.
This is useful when you want to asyncronously add functions to a queue without woring that they will execute in the order in which they were added.
You can see the depth of the queue by reading queue.length() like this:
const { Queue } = require('qfunc');
const queue = new Queue();
queue.enqueue(async () => {
await new Promise(resolve => setTimeout(resolve, 500));
console.log('A');
});
queue.enqueue(async () => {
await new Promise(resolve => setTimeout(resolve, 500));
console.log('B');
});
console.log(queue.length());In the above example, the queue length will be 1 because the first function will already have been dequeued and started leaving only one function on the queue.
You can also read isEmpty() which returns a boolean:
const { Queue } = require('qfunc');
const queue = new Queue();
queue.enqueue(async () => {
await new Promise(resolve => setTimeout(resolve, 500));
console.log('A');
});
queue.enqueue(async () => {
await new Promise(resolve => setTimeout(resolve, 500));
console.log('B');
});
console.log(queue.isEmpty());The above example results in false because the queue is not empty.
The implementation is super simple and far fewer lines than even this README.md. See what I mean by looking here: https://github.com/anders94/qfunc/blob/main/lib/index.js
Here's a more expressive example that uses an interval to continually show the length of the queue and prove that things operate in order:
const { Queue } = require('qfunc');
const timeout = (ms) => {
return new Promise(resolve => setTimeout(resolve, ms));
};
const queue = new Queue();
const i = setInterval(() => console.log(queue.length()), 250);
console.log('queue 1');
queue.enqueue(async () => {
console.log('start 1');
await timeout(1000);
console.log('end 1');
});
console.log('queue 2');
queue.enqueue(async () => {
console.log('start 2');
await timeout(1000);
console.log('end 2');
});
setTimeout(() => {
console.log('queue 3');
queue.enqueue(async () => {
console.log('start 3');
await timeout(1000);
console.log('end 3');
clearInterval(i);
}, 1100);
});Output:
queue 1
start 1
queue 2
queue 3
2
2
2
end 1
start 2
1
1
1
1
end 2
start 3
0
0
0
0
end 3
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