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5-closure.js
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44 lines (34 loc) · 805 Bytes
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'use strict';
const keyCollector = (keys) => {
let finished = false;
let count = 0;
let done = null;
const data = {};
const set = (key, value) => {
if (!finished) {
const expected = keys.includes(key);
const has = data[key] !== undefined;
if (!has && expected) count++;
data[key] = value;
if (count === keys.length) {
finished = true;
if (done) done(data);
}
}
};
const then = (resolve) => (done = resolve);
return { set, then };
};
// Usage
const main = async () => {
const ac = keyCollector(['fileName', 'userName']);
setTimeout(() => {
ac.set('fileName', 'marcus.txt');
}, 100);
setTimeout(() => {
ac.set('userName', 'Marcus');
}, 200);
const result = await ac;
console.log(result);
};
main();