32 lines
934 B
JavaScript
32 lines
934 B
JavaScript
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'use strict';
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const pLimit = require('p-limit');
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class EndError extends Error {
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constructor(value) {
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super();
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this.value = value;
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}
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}
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// the input can also be a promise, so we `Promise.all()` them both
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const finder = el => Promise.all(el).then(val => val[1] === true && Promise.reject(new EndError(val[0])));
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module.exports = (iterable, tester, opts) => {
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opts = Object.assign({
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concurrency: Infinity,
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preserveOrder: true
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}, opts);
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const limit = pLimit(opts.concurrency);
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// start all the promises concurrently with optional limit
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const items = Array.from(iterable).map(el => [el, limit(() => Promise.resolve(el).then(tester))]);
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// check the promises either serially or concurrently
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const checkLimit = pLimit(opts.preserveOrder ? 1 : Infinity);
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return Promise.all(items.map(el => checkLimit(() => finder(el))))
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.then(() => {})
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.catch(err => err instanceof EndError ? err.value : Promise.reject(err));
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};
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