async-singleton

Promiseをひとつだけ実行するやつ

code:script.js

export function asyncSingleton(callback) {

if (typeof callback !== 'function') throw new Error('argument is not function.')

let queue = [];

let isRunning = false;

return (...parameters) => new Promise(async resolve => {

console.log({isRunning});

if (isRunning) {

queue.forEach(pair => pair.resolve({state: 'canceled'}));

return;

}

isRunning = true;

resolve({result: await callback(...parameters), state: 'fullfilled'});

if (queue.length > 0) queue.forEach(async pair =>

pair.resolve({result: await callback(...pair.parameters), state: 'fullfilled'}));

queue = [];

isRunning = false;

});

}