57 lines
1.6 KiB
JavaScript
57 lines
1.6 KiB
JavaScript
/**
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* Execute promises in sequence one after another.
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*/
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async function sequence(promises) {
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return promises.reduce((promise, func) =>
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promise.then(result => func().then(Array.prototype.concat.bind(result))), Promise.resolve([]));
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}
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/**
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* Return first resolved promise as the result.
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*/
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async function first(promises) {
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return Promise.all(promises.map((p) => {
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// If a request fails, count that as a resolution so it will keep
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// waiting for other possible successes. If a request succeeds,
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// treat it as a rejection so Promise.all immediately bails out.
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return p.then(
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(val) => Promise.reject(val),
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(err) => Promise.resolve(err)
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);
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})).then(
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// If '.all' resolved, we've just got an array of errors.
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(errors) => Promise.reject(errors),
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// If '.all' rejected, we've got the result we wanted.
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(val) => Promise.resolve(val)
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);
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}
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/**
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* Delay promise
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*/
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async function delay(duration) {
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return new Promise((resolve) => setTimeout(resolve, duration));
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}
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/**
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* Timeout promise after a set time in ms
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*/
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async function timeout(timeoutMs, promise, message = 'Timed out') {
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return Promise.race([
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promise,
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new Promise(function (resolve, reject) {
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setTimeout(function () {
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reject(message);
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}, timeoutMs);
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})
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]);
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}
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/**
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* Return most common value from given array.
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*/
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function mostCommonValue(array) {
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return array.sort((a, b) => array.filter(v => v === a).length - array.filter(v => v === b).length).pop();
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}
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module.exports = { sequence, first, delay, timeout, mostCommonValue }; |